* Replace all uses of StrPath, BytesPath, and AnyPath in Python 2 stubs.
* Add StrOrBytesPath as preferred alias for AnyPath.
* Replace all remaining AnyPath instances with StrOrBytesPath.
* Mark AnyPath as obsolete.
Part of #5470
A security fix added a "separator" argument to several URL parsing
functions and method in point releases:
* 3.6.13
* 3.7.10
* 3.8.8
* 3.9.2
Until all these versions are available on the GitHub Actions runners,
we need to whitelist the functions in the stubtests.