Aromatisation of a ring which includes nitrogen Question

Complete the following reaction sequence:


Answer

 

My solution
I was able to complete all the steps except for the last one. This is what I ended up with:

What I'm not getting is how the $\ce{-OH}$ groups are removed and the ring is aromatised. If anyone could provide me with a mechanism for the same, it would be really helpful.
This would be the mechanism I propose for the reaction:

 

I have taken the $\ce{pH}$ of the medium to be $4.5$. That should explain the protonation of the $\ce{-OH}$ groups.