Bump virtualenv from 20.1.0 to 20.2.1 in /.github/workflows

[cjolowicz]

Bumps virtualenv from 20.1.0 to 20.2.1.

Changelog

Sourced from virtualenv's changelog.

v20.2.1 (2020-11-23)

No significant changes.

v20.2.0 (2020-11-21)

Features - 20.2.0

- Optionally skip VCS ignore directive for entire virtualenv directory, using option :option:`no-vcs-ignore`, by default ``False``. (`[#2003](https://github.com/pypa/virtualenv/issues/2003) <https://github.com/pypa/virtualenv/issues/2003>`_)
- Add ``--read-only-app-data`` option to allow for creation based on an existing
  app data cache which is non-writable.  This may be useful (for example) to
  produce a docker image where the app-data is pre-populated.
.. code-block:: dockerfile
  ENV \
      VIRTUALENV_OVERRIDE_APP_DATA=/opt/virtualenv/cache \
      VIRTUALENV_SYMLINK_APP_DATA=1
  RUN virtualenv venv &amp;&amp; rm -rf venv
  ENV VIRTUALENV_READ_ONLY_APP_DATA=1
  USER nobody
  # this virtualenv has symlinks into the read-only app-data cache
  RUN virtualenv /tmp/venv

Patch by :user:asottile. ([#2009](https://github.com/pypa/virtualenv/issues/2009) &lt;https://github.com/pypa/virtualenv/issues/2009&gt;_)
Bugfixes - 20.2.0

• Fix processing of the VIRTUALENV_PYTHON environment variable and make it multi-value as well (separated by comma) - by :user:pneff. ([#1998](https://github.com/pypa/virtualenv/issues/1998) <https://github.com/pypa/virtualenv/issues/1998>_)

Commits

• e8041cf release 20.2.1
• 13c5369 Remove high constraint for importlib-metadata (#2020)
• 6fab6a8 Merge pull request #2017 from pypa/release-20.2.0
• e6f7485 release 20.2.0
• af08309 Add --readonly-app-data option (#2009)
• ed7ceb5 conftest.py: Make coverage optional (#2008)
• 271dd73 Use environment files for adding to PATH on Github Action (#2016)
• 87877f8 Also skip xonsh tests on Python 3.10 (#2013)
• 25c45cf [pre-commit.ci] pre-commit autoupdate (#2011)
• 9708b54 Optionally skip creation of .gitignore in virtualenv directory (#2004)
• Additional commits viewable in compare view

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