Switch to USE_PYTHON= pep517 pytest
Add devel/py-wheel as a BUILD_DEPENDS -- not mentioned in upstream
pyproject.toml, but clearly needed for building.
Add security/gnupg, devel/git and devel/mercurial to TEST_DEPENDS
since so many tests require them. Do not add (eg.) sysutils/coreutils
for dir or ressurect the expired devel/py-hg-git for particular
tests.
Delete all patch files as these are no longer necessary
ChangeLog: https://github.com/pypa/setuptools_scm/blob/v7.1.0/CHANGELOG.rst