Update changlog CI to use a pre-built workflow.

[WilliamJamieson]

This PR updates the CI to use a pre-built changelog workflow, which is functionally equivalent to the current one

Checklist

• added entry in CHANGES.rst (either in Bug Fixes or Changes to API)
• updated relevant tests
• updated relevant documentation
• updated relevant milestone(s)
• added relevant label(s)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (4d44cd8) 84.31% compared to head (5ec670d) 84.31%.

❗ Current head 5ec670d differs from pull request most recent head 20eeeec. Consider uploading reports for the commit 20eeeec to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #233   +/-   ##
=======================================
  Coverage   84.31%   84.31%           
=======================================
  Files          35       35           
  Lines        6452     6452           
=======================================
  Hits         5440     5440           
  Misses       1012     1012           

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[zacharyburnett]

LGTM, some minor tweaks to minimize changes to the PR check screen

[zacharyburnett]

looks like it's sticking up on the changelog format:

docutils.utils.SystemMessage: <rst-doc>:272: (SEVERE/4) Title level inconsistent:

ramp_fitting
~~~~~~~~~~~~

I'll go through an fix these

[zacharyburnett]

looks like that fixed it; I just used restructuredtext-lint to find issues

pip install restructuredtext-lint
restructuredtext-lint CHANGES.txt