While the sentence is not technically a question, the use of a question mark indicates that the speaker is inviting a response from others.
In that respect, the question mark conveys the speaker's meaning in a way that could not otherwise be indicated in writing without the use of additional words.
So I'd say that this use of the question mark is correct when recording informal speech like this - but formally, it should really be reserved for actual questions.
english.stackexchange.com/users/303/Steve Melnikoff
I now have a bit more time to fix bugs etc
but I'm open to offers if anyone wants to help maintain this module with me?
This sentence/question is different than a statement and different than the " up-talking " that happens when people occasionally (or all the #$! time) raise the pitch of their sentences and phrases.
If the person said I now have a bit more time to fix bugs etc
but I'm open to offers if anyone wants to help maintain this module with me.
they are merely stating that they have time and are open to offers for help.
By raising the pitch at then end (spoken) or adding the question mark (written) they are implying a question: Would anyone like to offer to help me?
I hear this type of usage commonly.
We will proceed with the next item on the agenda, unless there are any questions?
no?
Ok, moving along...
english.stackexchange.com/users/380/Mr. Shiny and New 安宇
In written speech this is a questionable usage.
Nevertheless, when speaking, people frequently end declarative sentences with a rising intonation to invite the listener to consider the sentence as an invitation to agreement or action.
One hears this kind of thing especially in the southern United States.
"
Anyway, I had this Chrysler?
It had a four-barrel carburetor?"
Here the speaker is making declarations about a car, but making them sound like questions so that the listener will respond (probably nodding or saying "uh-huh") in a way that indicates interest in and understanding of the story being related.
If your example sentence were spoken this way, listeners would likely interpret it as a request for help, not merely a statement of a condition.
But if you write it, you should leave out the question mark.
Addendum
Since I wrote this, I've become aware that the practice of ending declarative sentences with a rising intonation actually has a name: uptalk
n a manner of speaking in which declarative sentences are uttered with rising intonation at the end, as if they were questions.
english.stackexchange.com/users/2303/Robusto
This is something you see very often in spoken language.
As we talk, we are making a syntactic structure.
It's common for syntactic structures to change, or be re-analyzed, as we go along.
So in this case, "if anyone wants to help maintain this module with me?" is reanalyzed, on the fly, as "Does anyone want to help maintain this module with me?"
In careful writing, since readers can go back and check what you said previously, this sort of on the fly reanalysis is discouraged.
english.stackexchange.com/users/78/Alan Hogue
Just for the sake of anyone reading, I found this thread when I googled about this issue because Microsoft Word grammar checker tried to tell me that I should put a question mark at the end of this sentence: 'If you can do them in advance of this deadline then so much the better.'
I completely disagree with such a usage in written English.
english.stackexchange.com/users/276846/Aden
Steve Melnikoff's is the best analysis, but can be taken further.
I think with the 'quick text parsing' that is becoming a part of our language pragmatics given the 'texting'/'information overload' age, punctuation marks in written materials are changing their purpose.
As Melnikoff point out, in the example you use the question mark is inviting a response.
The reader can visually 'skim' right through e.g., an email, to get at what his interlocutor wants him to respond to.
The question mark is in effect basically an abbreviation with respect to what would have been written twenty years ago, when more verbiage would need to be required to have the request not come off in writing as rude.
English in the twenty-first century (in a particular context, at any rate).
english.stackexchange.com/users/26327/Merk
Another example which I don't think quite fits any of the explanations above occurs in social media where the question mark is used at the end of declarative statements intended as accusations or harsh judgements.
The context shows the statement to be actually declarative, though it could be considered an interrogative in other contexts.
However, the poster doesn't want to come across as socially abrasive or intends to leave room for backing off of the judgement in case there is a backlash of disagreement or reverse judgement.
For example:
"She is a narcissist?""A guy that overweight shouldn't be going to McDonald's?""Those
so-called 'statues' are just toys for overgrown children?"
In this case it is a fundamentally disingenuous usage, because the poster clearly has a strong negative opinion about someone or some group, such that they want to express it, but don't feel either confident enough in themselves or the view to post it as a genuine declaration.
Another way to put it would be as an unconvincing attempt at avoiding social liability.
english.stackexchange.com/users/239979/Xandyr Wlkyr
For example, I found the following sentence written by a native English speaker (UK) so I'm going to assume that he knows how to put it the right way, although I wouldn't use this form.   I now have a bit more time to fix bugs  etc but I'm open to offers if anyone  wants to help maintain this module  with me?   Is it correct or is the question mark misused here?
Is the question mark misused in affirmative sentences?
english.stackexchange.com
<grammar><punctuation><question-mark><if-question>
english.stackexchange.com/questions/5619
english.stackexchange.com/users/2252/dag729
This use of the question mark would be viewed by some as unacceptable or at the very least questionable. Other people would recommend limiting it to informal situations. In any case, the question mark here is inviting a response from others in a way that would require the use of additional words. As such, it may still be understood without much problem. Some people do not agree with this usage in written English. It would be correct in informal speech, not for formally.Text parsing has caused us to change the use of punctuation marks.The statement is actually a declaration, though in another context could be considered an interrogative.
This use of the question mark would be viewed by some as unacceptable or at the very least questionable. Other people would recommend limiting it to informal situations. In any case, the question mark here is inviting a response from others in a way that would require the use of additional words. As such, it may still be understood without much problem. While the sentence is not technically a question, the use of a question mark indicates that the speaker is inviting a response from others.  When speaking, people frequently end declarative sentences with a rising intonation to invite the listener to consider the sentence as an invitation to agreement or action and this can be seen as the equivalent. Another example which I don't think quite fits any of the explanations above occurs in social media where the question mark is used at the end of declarative statements intended as accusations or harsh judgements.  
Although this may be questionable in formal,  written usage, and not technically a question, the question mark conveys the speaker's meaning and indicates that a response is invited. This is a shorter way of writing that what would have ben used traditionally, but nowadays it is not considered rude. This use of the question mark would be viewed by some as unacceptable or at the very least questionable. Other people would recommend limiting it to informal situations. In any case, the question mark here is performing a function that would otherwise require more words and is inviting a response from the reader. As such, it may still be understood without much problem.
Some people do not agree with this usage in written English. It would be correct in informal speech, not for formally. Text parsing has caused us to change the use of punctuation marks. The statement is actually a declaration, though in another context could be considered an interrogative.
While the sentence is not technically a question, the use of a question mark indicates that the speaker is inviting a response from others.   When speaking, people frequently end declarative sentences with a rising intonation to invite the listener to consider the sentence as an invitation to agreement or action and this can be seen as the equivalent. Another example which I don't think quite fits any of the explanations above occurs in social media where the question mark is used at the end of declarative statements intended as accusations or harsh judgements.  
Whilst the sentence is not technically a question, the question mark is performing a function that would otherwise require more words and is essentially inviting a response from the reader. This use of the question mark is possible acceptable in informal speech but should be avoided in formal situations. Some people would view this use of the question mark as either questionable or completely unacceptable.