tests: drop py2 support from test-doctest.py

tests: drop py2 support from test-demandimport.py

tests: optional PEP 657 error location in test-extension.t (issue6781)

tests: filter out PEP 657 error locations in tracebacks (issue6780) https://docs.python.org/3/whatsnew/3.11.html#whatsnew311-pep657

pytype: add coverage for parts of hgext There are tons of things to fix here (which have been blacklisted for now), but this should help prevent further regressions.

convert: stop passing str to the dateutil API in darcs I'm sure there's a bunch more stuff in here that's broken, but this was flagged by pytype.

typing: suppress a couple of attribute-errors in convert I thought these might be real issues, but they're not.

hooklib: force an exception wrapped by errors.Abort to bytestr Flagged by PyCharm and pytype.