use towncrier to handle change log entries and update new pull request checklist

[zacharyburnett]

follow-on to spacetelescope/romancal#1375

old checklist

Checklist

• Schema changes discussed at RAD Review Board meeting
• Added entry in CHANGES.rst under the corresponding subsection
• Updated relevant roman_datamodels utilities and tests
• Passed romancal regression testing on Jenkins / PLWishMaster. Link: https://plwishmaster.stsci.edu:8081/job/RT/job/romancal/XXX/

new checklist

Tasks

• update or add relevant rad tests
• update relevant docstrings and / or docs/ page
• Does this PR change schema?
  • schema changes were discussed at RAD Review Board meeting
• Does this PR change any API used downstream? (if not, label with no-changelog-entry-needed)
  • write news fragment(s) in changes/: echo "changed something" > changes/<PR#>.<changetype>.rst (see below for change types)
  • update relevant roman_datamodels utilities and tests
  • start a romancal regression test with this branch installed ("git+https://github.com/<fork>/rad@<branch>")

news fragment change types...

• changes/<PR#>.apichange.rst: change to public API
• changes/<PR#>.bugfix.rst: fixes an issue
• changes/<PR#>.general.rst: infrastructure or miscellaneous change

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.45%. Comparing base (c1811ab) to head (717bd4e).
Report is 182 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #442      +/-   ##
==========================================
+ Coverage   95.38%   95.45%   +0.06%     
==========================================
  Files           4        4              
  Lines         195      198       +3     
==========================================
+ Hits          186      189       +3     
  Misses          9        9              

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[PaulHuwe]

I thought the existing changelog file would be converted to JSON, which would then be used going forward. Did I misunderstand?

[zacharyburnett]

I thought the existing changelog file would be converted to JSON, which would then be used going forward. Did I misunderstand?

I don't know about that, I considered modifying the existing changelog entries to make the issue numbers have links to the GitHub issue but I'm not sure how useful old changelog entries are (or who looks at them). This PR just changes how new sections are added to CHANGES.rst upon release

[PaulHuwe]

Just some formatting changes for future PRs.

[PaulHuwe]

LGTM