This issue came in because of commit 9b3f65096e a month ago.
`bdist_egg` has always been missing from the command list, but
that wasn't a problem because missing commands were simply
ignored by the validation. After that commit we started raising
a RuntimeError instead.

MAINT: Add dist_info to "other" setup.py commands.

The follwing changes are made to 'setup.py'.

- Add 'dist_info' to the valid 'setup.py' commands. The 'dist_info'
  command was added to setuptools in 2017 and we were following the
  unrecognized command path in setup.py which raised a warning.
- Add 'version' to the recognized information commands, it came in with
  the move to versioneer.
- Include the arguments passed to 'setup.py' when the unrecognized
  command warning is raised. This will aid in maintaining the command
  checks in the future.

Before this change, it would give a random syntax error somewhere
in `versioneer`.

If sdist uses setuptools there can be problems, see gh-7127.

The new tags look like '1.21.0.dev0+98.gaa0453721f', where '98' is the
number of commits since the 1.21.0 branch was started and 'aa0453721f'.
The chosen form may be specified in the 'setup.cfg' file. This PR adds
two new files 'numpy/_version.py' and 'numpy/version.py'. The latter
is kept because it is part of the public API and is actually used by
some downstream projects, but it is no longer dynamically created.

See https://github.com/python-versioneer/python-versioneer/ for more
information.

We missed a few first time around.

This adds a timestamp to development versions of NumPy. We used to do
this for NumPy nightly builds so that pip would pickup the latest
version, but pip 20.3 breaks with that as there is disagreement between
the wheel name and the internal version.

Closes #17885.

- Update setup.py
- Update pavement.py
- Add 1.21.0-note.rst
- Update npyconfig.h
- Clear release/upcoming_changes