docs(backport): Add automatic release notes config file

[meeseeksmachine]

Backport PR #2476: docs: Add automatic release notes config file

* Backport PR https://github.com/scikit-hep/pyhf/pull/2476
* Add a .github/release.yml file to configure the automatic release notes
  that GitHub can generate on a release.
   - https://docs.github.com/en/repositories/releasing-projects-on-github/automatically-generated-release-notes
* Ignore contributions from Dependabot and pre-commit-ci from the
  release notes.

Co-authored-by: Matthew Feickert <[email protected]>

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

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Additional details and impacted files

@@                Coverage Diff                @@
##             release/v0.7.x    #2498   +/-   ##
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  Coverage                  ?   96.45%           
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  Files                     ?       69           
  Lines                     ?     4545           
  Branches                  ?      648           
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  Hits                      ?     4384           
  Misses                    ?      125           
  Partials                  ?       36           

Flag	Coverage Δ
unittests-3.10	96.25% <ø> (?)
unittests-3.7	96.23% <ø> (?)
unittests-3.8	96.28% <ø> (?)
unittests-3.9	96.30% <ø> (?)

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