feat: use the CHANGELOG file in the `release-github` action

[klmcadams]

Use the CHANGELOG file in the release-github action

• Search pyproject.toml file for towncrier filename (the path to the changelog file)
• If the filename does not exist, then release to GitHub without using the changelog file
• If the changelog file exists, release to GitHub using the changelog file

Note: this will be a breaking change due to the new required "token" input

Closes #460

[ansys-reviewer-bot[bot]]

Thanks for opening a Pull Request. If you want to perform a review write a comment saying:

@ansys-reviewer-bot review

[klmcadams]

After testing, this is what the release notes look like:

Release notes with changelog.rst Release notes with CHANGELOG.md

The RST changelog doesn't render well since the release notes are in markdown. Also, the entire changelog is copied into the release notes, not just the section for that release.

Some ideas:

• Translate RST changelog files to MD in the action
• Use regex (?) to parse the CHANGELOG file & retrieve only the section of the changelog for the corresponding tag
  • Potentially put the tagged section in a temporary file and use that file in the softprops/action-gh-release

Thoughts/suggestions? There could be more efficient ways to do this that I'm not thinking of

[RobPasMue]

Yeah... the rST file version looks horrible. That one would need some conversion to MD for sure.

Some ideas:

• Translate RST changelog files to MD in the action
• Use regex (?) to parse the CHANGELOG file & retrieve only the section of the changelog for the corresponding tag
  • Potentially put the tagged section in a temporary file and use that file in the softprops/action-gh-release

The ideas seem fine to me. Another option that occurred to me is to check the git history of the changelog and extract the last commit to it. If things are done how they should, this section will contain the release notes for the current release. If they are in RST we can convert them, to MD. If it's already in MD you just need to embed it.