Add python package Pygments to rst-lint venv

[bobidle]

Proposed Changes

1. Add Pygments to venv of rst-lint linter

• used to scan the code block of rst files
• removes the warning like this

WARNING path/to/file.rst:52 Cannot analyze code. Pygments package not found.

Readiness Checklist

Author/Contributor

• Add entry to the CHANGELOG listing the change and linking to the corresponding issue (if appropriate)
• If documentation is needed for this change, has that been included in this pull request

Reviewing Maintainer

• Label as breaking if this is a large fundamental change
• Label as either automation, bug, documentation, enhancement, infrastructure, or performance

[nvuillam]

Thanks for your PR :)