[Python] Add support for Python 3.9 except macOS wheel and Windows wheel

[asfimport]

Now that Python 3.9 is out, there should be wheels built for it.

I have started an initial stab at building the 3.9 wheels and have tested with the docker image python:3.9-buster with a manylinux2010 build of pyarrow.

The goal of this change will be to get a review and identify what is or is not working at this point.

Reporter: Terence Honles / @terencehonles
Assignee: Terence Honles / @terencehonles

Related issues:

• Pyarrow doesn't install with pip on Python 3.9+ (duplicates)
• [Python] Failed to build pyarrow on python 3.9 (duplicates)
• Python 3.9 support (duplicates)
• [Python] Add support for Python 3.9 macOS wheels (relates to)
• [Python] Add support for Python 3.9 windows wheels (relates to)

PRs and other links:

• GitHub Pull Request #8386
• GitHub Pull Request #8778

_{Note: This issue was originally created as ARROW-10224. Please see the migration documentation for further details.}

[asfimport]

Kouhei Sutou / @kou:
Issue resolved by pull request 8386
#8386