ref(releases): Move release serializers into releases module

[cmanallen]

Releated: #95926

Part two. See the plan here.

[codecov]

Codecov Report

❌ Patch coverage is 96.63677% with 15 lines in your changes missing coverage. Please review.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/sentry/releases/serializers/release.py	95.93%	12 Missing ⚠️
src/sentry/releases/serializers/release_dupe.py	93.61%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #95932      +/-   ##
==========================================
+ Coverage   81.49%   85.35%   +3.85%     
==========================================
  Files       10581    10587       +6     
  Lines      609915   609948      +33     
  Branches    23982    23982              
==========================================
+ Hits       497029   520594   +23565     
+ Misses     112602    89070   -23532     
  Partials      284      284              

[getsantry]

This pull request has gone three weeks without activity. In another week, I will close it.

But! If you comment or otherwise update it, I will reset the clock, and if you add the label WIP, I will leave it alone unless WIP is removed ... forever!

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"A weed is but an unloved flower." ― Ella Wheeler Wilcox 🥀