Create GitHub release notes

[vivus-ignis]

What this PR does / why we need it:
Splitting #179 into smaller parts

Which issue(s) this PR fixes:
gardenlinux/gardenlinux#3054

[codecov]

Codecov Report

❌ Patch coverage is 47.01493% with 71 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.06%. Comparing base (76dcb4e) to head (38b3d1c).
⚠️ Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
src/gardenlinux/github/release_notes/sections.py	47.54%	32 Missing ⚠️
src/gardenlinux/github/release_notes/helpers.py	33.33%	16 Missing ⚠️
src/gardenlinux/github/release_notes/__init__.py	16.66%	15 Missing ⚠️
src/gardenlinux/github/__main__.py	61.90%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #202      +/-   ##
==========================================
- Coverage   93.23%   89.06%   -4.17%     
==========================================
  Files          30       33       +3     
  Lines        1375     1500     +125     
==========================================
+ Hits         1282     1336      +54     
- Misses         93      164      +71     

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[Akendo]

Just some small changes, it looks good else.