Update
python-certifi-win32 is not maintained anymore as pointed out in the comment.
Use the drop-in library pip-system-certs instead.
If you are using Windows and you have already imported the CA in the trusted DB store, you can install the package python-certifi-win32 that automagically will use the same certificates from the Trusted DB store.
pip install python-certifi-win32
Then your code should start to work
See:
Python Requests with wincertstore
https://gitlab.com/alelec/python-certifi-win32