Update virtualenv to 20.0.26

[pyup-bot]

This PR updates virtualenv from 20.0.18 to 20.0.26.

Changelog

20.0.25

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- Fix that when the ``app-data`` seeders image creation fails the exception is silently ignored. Avoid two virtual environment creations to step on each others toes by using a lock while creating the base images. By :user:`gaborbernat`. (`1869 <https://github.com/pypa/virtualenv/issues/1869>`_)

20.0.24

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- How seeding mechanisms discover (and automatically keep it up to date) wheels at :ref:`wheels` - by :user:`gaborbernat`. (`1821 <https://github.com/pypa/virtualenv/issues/1821>`_)
- How distributions should handle shipping their own embedded wheels at  :ref:`distribution_wheels` - by :user:`gaborbernat`. (`1840 <https://github.com/pypa/virtualenv/issues/1840>`_)

20.0.23

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- Fix typo in ``setup.cfg`` - by :user:`RowdyHowell`. (`1857 <https://github.com/pypa/virtualenv/issues/1857>`_)

20.0.22

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- Relax ``importlib.resources`` requirement to also allow version 2 - by :user:`asottile`. (`1846 <https://github.com/pypa/virtualenv/issues/1846>`_)
- Upgrade embedded setuptools to ``44.1.1`` for python 2 and ``47.1.1`` for python3.5+ - by :user:`gaborbernat`. (`1855 <https://github.com/pypa/virtualenv/issues/1855>`_)

20.0.21

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- Fix virtualenv fails sometimes when run concurrently, ``--clear-app-data`` conflicts with :option:`clear` flag when
abbreviation is turned on. To bypass this while allowing abbreviated flags on the command line we had to move it to
:option:`reset-app-data` - by :user:`gaborbernat`. (`1824 <https://github.com/pypa/virtualenv/issues/1824>`_)
- Upgrade embedded ``setuptools`` to ``46.4.0`` from ``46.1.3`` on Python ``3.5+``, and ``pip`` from ``20.1`` to ``20.1.1`` - by :user:`gaborbernat`. (`1827 <https://github.com/pypa/virtualenv/issues/1827>`_)
- Seeder pip now correctly handles ``--extra-search-dir`` - by :user:`frenzymadness`. (`1834 <https://github.com/pypa/virtualenv/issues/1834>`_)

20.0.20

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- Fix download fails with python 3.4 - by :user:`gaborbernat`. (`1809 <https://github.com/pypa/virtualenv/issues/1809>`_)
- Fixes older CPython2 versions use ``_get_makefile_filename`` instead of ``get_makefile_filename`` on ``sysconfig`` - by :user:`ianw`. (`1810 <https://github.com/pypa/virtualenv/issues/1810>`_)
- Fix download is ``True`` by default - by :user:`gaborbernat`. (`1813 <https://github.com/pypa/virtualenv/issues/1813>`_)
- Fail ``app-data`` seed operation when wheel download fails and better error message - by :user:`gaborbernat`. (`1814 <https://github.com/pypa/virtualenv/issues/1814>`_)

20.0.19

~~~~~~~~~~~~~~~~~~
- Fix generating a Python 2 environment from Python 3 creates invalid python activator - by :user:`gaborbernat`. (`1776 <https://github.com/pypa/virtualenv/issues/1776>`_)
- Fix pinning seed packages via ``app-data`` seeder raised ``Invalid Requirement`` - by :user:`gaborbernat`. (`1779 <https://github.com/pypa/virtualenv/issues/1779>`_)
- Do not stop interpreter discovery if we fail to find the system interpreter for a executable during discovery
- by :user:`gaborbernat`. (`1781 <https://github.com/pypa/virtualenv/issues/1781>`_)
- On CPython2 POSIX platforms ensure ``syconfig.get_makefile_filename`` exists within the virtual environment (this is used by some c-extension based libraries - e.g. numpy - for building) - by :user:`gaborbernat`. (`1783 <https://github.com/pypa/virtualenv/issues/1783>`_)
- Better handling of options :option:`copies` and :option:`symlinks`. Introduce priority of where the option is set
to follow the order: CLI, env var, file, hardcoded. If both set at same level prefers copy over symlink. - by
:user:`gaborbernat`. (`1784 <https://github.com/pypa/virtualenv/issues/1784>`_)
- Upgrade pip for Python ``2.7`` and ``3.5+`` from ``20.0.2`` to ``20.1`` - by :user:`gaborbernat`. (`1793 <https://github.com/pypa/virtualenv/issues/1793>`_)
- Fix CPython is not discovered from Windows registry, and discover pythons from Windows registry in decreasing order
by version - by :user:`gaborbernat`. (`1796 <https://github.com/pypa/virtualenv/issues/1796>`_)
- Fix symlink detection for creators - by :user:`asottile` (`1803 <https://github.com/pypa/virtualenv/issues/1803>`_)

Links

• PyPI: https://pypi.org/project/virtualenv
• Changelog: https://pyup.io/changelogs/virtualenv/
• Homepage: https://virtualenv.pypa.io/

[pyup-bot]

Closing this in favor of #1236