Fix deprecation warning with Python 3.8 triggered by vendored urllib3#1618

tsnoam merged 1 commit intomasterpython-telegram-bot/python-telegram-bot:masterfrom

fix_vendored_urllib3_py38_deprecation_warnpython-telegram-bot/python-telegram-bot:fix_vendored_urllib3_py38_deprecation_warnCopy head branch name to clipboard