Unvendor everything

[WToma]

Please answer these questions before submitting your pull requests. Thanks!

1. What GitHub issue is this PR addressing? Make sure that there is an accompanying issue to your PR.

   SNOW-507597

   This is a workaround to MemoryError: Cannot allocate write+execute memory for ffi.callback() pyca/pyopenssl#873. It looks like that up-to-date versions of requests and urllib3 avoid the issues with pyopenssl described in that issue, so the connector is once again able to function.
   However I wasn't able to get the OCSP code to work. So the only way to use this is with insecure_mode=True.

2. Fill out the following pre-review checklist:

   • I am adding a new automated test(s) to verify correctness of my new code
   • I am adding new logging messages
   • I am modifying authorization mechanisms
   • I am adding new credentials
   • I am modifying OCSP code
   • I am adding a new dependency: technically this is adding new dependencies on requests and urllib3, since they're no longer vendored.

3. Please describe how your code solves the related issue.

   Please write a short description of how your code change solves the related issue.