Apparently, the appengine package which is in urllib3.contrib is not present anymore in the modern versions of urllib3 but it is still required using the framework python-telegram-bot v13.11 (source telegram/utils/request.py line 44).
ModuleNotFoundError: No module named 'urllib3.contrib.appengine'
It is possible to solve it using a previous version of urllib3 next to the requests library.
pip install urllib3==1.26.15