Bump virtualenv from 20.2.1 to 20.4.1

[dependabot]

Bumps virtualenv from 20.2.1 to 20.4.1.

Changelog

Sourced from virtualenv's changelog.

v20.4.1 (2021-01-31)

Bugfixes - 20.4.1

- Bump embedded pip and setuptools packages to latest upstream supported (``21.0.1`` and ``52.0.0``) - by :user:`gaborbernat`. (`[#2060](https://github.com/pypa/virtualenv/issues/2060) <https://github.com/pypa/virtualenv/issues/2060>`_)
v20.4.0 (2021-01-19)
Features - 20.4.0

• On the programmatic API allow passing in the environment variable dictionary to use, defaults to os.environ if not specified - by :user:gaborbernat. ([#2054](https://github.com/pypa/virtualenv/issues/2054) <https://github.com/pypa/virtualenv/issues/2054>_)

Bugfixes - 20.4.0

- Upgrade embedded setuptools to ``51.3.3`` from ``51.1.2`` - by :user:`gaborbernat`. (`[#2055](https://github.com/pypa/virtualenv/issues/2055) <https://github.com/pypa/virtualenv/issues/2055>`_)
v20.3.1 (2021-01-13)
Bugfixes - 20.3.1

• Bump embed pip to 20.3.3, setuptools to 51.1.1 and wheel to 0.36.2 - by :user:gaborbernat. ([#2036](https://github.com/pypa/virtualenv/issues/2036) <https://github.com/pypa/virtualenv/issues/2036>_)
• Allow unfunctioning of pydoc to fail freely so that virtualenvs can be activated under Zsh with set -e (since otherwise unset -f and unfunction exit with 1 if the function does not exist in Zsh) - by :user:d125q. ([#2049](https://github.com/pypa/virtualenv/issues/2049) <https://github.com/pypa/virtualenv/issues/2049>_)
• Drop cached python information if the system executable is no longer present (for example when the executable is a shim and the mapped executable is replaced - such is the case with pyenv) - by :user:gaborbernat. ([#2050](https://github.com/pypa/virtualenv/issues/2050) <https://github.com/pypa/virtualenv/issues/2050>_)

v20.3.0 (2021-01-10)

Features - 20.3.0

- The builtin discovery takes now a ``--try-first-with`` argument and is first attempted as valid interpreters. One can
  use this to force discovery of a given python executable when the discovery order/mechanism raises errors -
  by :user:`gaborbernat`. (`[#2046](https://github.com/pypa/virtualenv/issues/2046) <https://github.com/pypa/virtualenv/issues/2046>`_)
Bugfixes - 20.3.0

• On Windows python 3.7+ distributions where the exe shim is missing fallback to the old ways - by :user:gaborbernat. ([#1986](https://github.com/pypa/virtualenv/issues/1986) <https://github.com/pypa/virtualenv/issues/1986>_)
• When discovering interpreters on Windows, via the PEP-514, prefer PythonCore releases over other ones. virtualenv is used via pip mostly by this distribution, so prefer it over other such as conda - by :user:gaborbernat. ([#2046](https://github.com/pypa/virtualenv/issues/2046) <https://github.com/pypa/virtualenv/issues/2046>_)

... (truncated)

Commits

• 61b2f6f release 20.4.1
• 0e85268 Bump setuptools and pip (#2060)
• 9093686 Merge pull request #2057 from pypa/release-20.4.0
• d47e0a5 release 20.4.0
• a9b0f3b Fix Windows failure (#2056)
• 40aec48 API: Allow passing on the environment variable as an argument (#2054)
• 4c95506 Upgrade embedded setuptools to 51.3.3 from 51.1.2 (#2055)
• 7185e57 Merge pull request #2051 from pypa/release-20.3.1
• 395696d release 20.3.1
• 7f83442 Clear stash if system executable is missing (#2050)
• Additional commits viewable in compare view

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[dependabot]

Superseded by #285.