devel/py-setuptools_scm: Update to 6.3.2 [1]

• Sort variables and use WRKSRC instead TEST_WRKSRC as the latter should be only used if it differs from WRKSRC. [1]

• Exclude some tests that require a more recent version of devel/py-virtualenv for now.

Changelog since 5.0.2:

https://github.com/pypa/setuptools_scm/blob/v6.3.2/CHANGELOG.rst

PR: 259445
Reported by: sunpoet [1]
MFH: No (feature release with new dependencies)