Models not able to run when packed with PyInstaller
## Environment info
- `transformers` version: 4.1.1
- Platform: Linux-5.8.0-48-generic-x86_64-with-glibc2.27
- Python version: 3.8.8
- PyTorch version (GPU?): 1.7.1 (False)
- Tensorflow version (GPU?): not installed (NA)
- Using GPU in script?: <fill in>
- Using distributed or parallel set-up in script?: <fill in>
- 

## Information
I am trying to create an executable for a flask application that uses [haystack](https://github.com/deepset-ai/haystack/) to serve a QA System. Haystack uses transformers.
If I run my API normally with python with `python api.py` it works fine. 
When I run `pyinstaller main.spec --distpath distAPI` the executable gets created fine (note that I will post main.spec down in the **To reproduce** section). However, when I run it with `./distAPI/main/main` I get the following error:
```
03/26/2021 16:45:35 - INFO - faiss -   Loading faiss with AVX2 support.
03/26/2021 16:45:35 - INFO - faiss -   Loading faiss.
Traceback (most recent call last):
  File "torch/_utils_internal.py", line 49, in get_source_lines_and_file
  File "inspect.py", line 979, in getsourcelines
  File "inspect.py", line 798, in findsource
OSError: could not get source code

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "main.py", line 8, in <module>
    from haystack.preprocessor.cleaning import clean_wiki_text
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "PyInstaller/loader/pyimod03_importers.py", line 531, in exec_module
  File "haystack/__init__.py", line 5, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "PyInstaller/loader/pyimod03_importers.py", line 531, in exec_module
  File "haystack/finder.py", line 9, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "PyInstaller/loader/pyimod03_importers.py", line 531, in exec_module
  File "haystack/retriever/base.py", line 9, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "PyInstaller/loader/pyimod03_importers.py", line 531, in exec_module
  File "haystack/document_store/base.py", line 6, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "PyInstaller/loader/pyimod03_importers.py", line 531, in exec_module
  File "haystack/preprocessor/utils.py", line 11, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "PyInstaller/loader/pyimod03_importers.py", line 531, in exec_module
  File "farm/data_handler/utils.py", line 18, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "PyInstaller/loader/pyimod03_importers.py", line 531, in exec_module
  File "farm/file_utils.py", line 26, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "PyInstaller/loader/pyimod03_importers.py", line 531, in exec_module
  File "transformers/__init__.py", line 91, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "PyInstaller/loader/pyimod03_importers.py", line 531, in exec_module
  File "transformers/modelcard.py", line 31, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "PyInstaller/loader/pyimod03_importers.py", line 531, in exec_module
  File "transformers/models/auto/__init__.py", line 20, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "PyInstaller/loader/pyimod03_importers.py", line 531, in exec_module
  File "transformers/models/auto/configuration_auto.py", line 28, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "PyInstaller/loader/pyimod03_importers.py", line 531, in exec_module
  File "transformers/models/deberta/__init__.py", line 25, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "PyInstaller/loader/pyimod03_importers.py", line 531, in exec_module
  File "transformers/models/deberta/modeling_deberta.py", line 462, in <module>
  File "torch/jit/_script.py", line 936, in script
  File "torch/jit/frontend.py", line 197, in get_jit_def
  File "torch/_utils_internal.py", line 56, in get_source_lines_and_file
OSError: Can't get source for <function c2p_dynamic_expand at 0x7f45cc4d85e0>. TorchScript requires source access in order to carry out compilation, make sure original .py files are available.
[104072] Failed to execute script main

```
It seems that it cannot get the source code for the `function c2p_dynamic_expand` in `transformers/models/deberta/modeling_deberta.py`.

## Additional information
This is a problem that already happened in the past when using Pyinstaller and Torch. 
See this issue [here](https://github.com/pyinstaller/pyinstaller/issues/4926) for example.

## To reproduce

Steps to reproduce the behavior:

1.Make a main.py :
```
from haystack.preprocessor.cleaning import clean_wiki_text

if __name__=='__main__':
    print('Hello World')

```
2. Install haystack 'pip install haystack`
3. See if it runs with `python main.py' (it should)
4. Install pyinstaller with `pip install pyinstaller`
5. Create a hooks/ folder containing the following files:
**hook-justext.py hook-packaging.py hook-requests.py hook-tokenizers.py hook-tqdm.py hook-transformers.py hook-filelock.py hook-numpy.py hook-regex.py hook-sacremoses.py hook-torch.py**
Each of these files should provide a hook for pyinstaller to to download that module. So, for example the hook-numpy.py file should be:
```
from PyInstaller.utils.hooks import collect_all

datas, binaries, hiddenimports = collect_all('numpy')
```
And so the rest of them.
6. create a main.spec file:
```
# -*- mode: python ; coding: utf-8 -*-
block_cipher = None
a = Analysis(['main.py'],
             pathex=['/Wexond/QandA/api'],
             binaries=[],
             datas=[],
             hiddenimports=['justext'],
             hookspath=['./hooks/'],    ## <-------------- Specifying the hooks
             runtime_hooks=[],
             excludes=[],
             win_no_prefer_redirects=False,
             win_private_assemblies=False,
             cipher=block_cipher,
             noarchive=False)
pyz = PYZ(a.pure, a.zipped_data, source_files_toc,
             cipher=block_cipher)
exe = EXE(pyz,
          a.scripts,
          [],
          exclude_binaries=True,
          name='main',
          debug=False,
          bootloader_ignore_signals=False,
          strip=False,
          upx=True,
          console=True )
coll = COLLECT(exe,
               a.binaries,
               a.zipfiles,
               a.datas,
               strip=False,
               upx=True,
               upx_exclude=[],
               name='main')
```
7. Pack the app with `pyinstaller main.spec --distpath distAPI`
8. Try to run it with `./distAPI/main/main` . 

You should now get the `OsError` metioned above..


Hello! Do you get the same error when not installing PyInstaller, instead using `haystack` in a virtual environment?<|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/master/CONTRIBUTING.md) are likely to be ignored.<|||||>Any update on this one?