[Chapel Merge] Update chpldoc dependencies to later versions

Branch: refs/heads/master
Revision: bc34539
Author: lydia-duncan
Log Message:

Merge pull request #16646 from lydia-duncan/chpldocPython3New

Update chpldoc dependencies to later versions
[reviewed by @mppf]

Due to trying to stay compliant with Python 2, chpldoc has had to rely on older versions of
its dependencies for a while now. Now that we’ve switched to relying on Python 3, we can
finally update these packages to later versions.

This updates the version for every chpldoc dependency except MarkupSafe, which does not
have a new version. This includes pinning to the latest version of our Chapel Sphinx domain
(which we had previously used a copy of due to imprecise version requirements that would
have broken chpldoc in previous releases. Note that I have not removed this copy of the
repo yet, as I was trying to avoid merge conflicts - I will remove it in a separate PR).

As a result of this change, our script to build the online documentation (which relies on
chpldoc) needed a couple of updates for deprecated features.

Resolves Cray/chapel-private#905

Passed a full paratest with futures. I also spot checked the built documentation with this
change and only observed positive changes (e.g. the update to Pygments means we now
highlight the import statement, etc.)

Modified Files:
M doc/rst/conf.py
M third-party/chpl-venv/chpldoc-requirements.txt

Compare: https://github.com/chapel-lang/chapel/compare/5b68005b8d4a...bc345393a3ba