devel/py-virtualenv: Update to 13.0.3

• Update to 13.0.3
• Update TEST_DEPENDS
• USE_GITHUB to get the test suite, since the sdist doesnt (yet) include it [1]
• Temporarily patch out versioned console_script (virtualenv) until USE_PYTHON=concurrent supports more granularity (coming soon)
• Add USE_PYTHON=concurrent support to virtualenv can be used for multiple python versioned
• Patch setup.py to fix test command invocation. Report upstream. [2]
• Tweak regression-test target to use the canonical setup.py variable

Changes:

https://virtualenv.pypa.io/en/latest/changes.html

[1] https://github.com/pypa/virtualenv/issues/714
[2] https://github.com/pypa/virtualenv/pull/773

Differential Revision: https://reviews.freebsd.org/D2703
Reviewed by: nivit (maintainer)
Approved by: nivit (maintainer)