Revert "Update requests library from v2.5.1 to v2.6.2 ff71b25e"

lib/requests/__init__.py

lib/requests/adapters.py

lib/requests/api.py

lib/requests/auth.py

lib/requests/compat.py

lib/requests/cookies.py

lib/requests/models.py

lib/requests/packages/__init__.py

lib/requests/packages/urllib3/__init__.py

lib/requests/packages/urllib3/_collections.py

lib/requests/packages/urllib3/connection.py

lib/requests/packages/urllib3/connectionpool.py

lib/requests/packages/urllib3/contrib/pyopenssl.py

lib/requests/packages/urllib3/exceptions.py

lib/requests/packages/urllib3/poolmanager.py

lib/requests/packages/urllib3/response.py

lib/requests/packages/urllib3/util/connection.py

lib/requests/packages/urllib3/util/ssl_.py

lib/requests/sessions.py

lib/requests/utils.py