feat(ci): create tag and merge commit manually

[paullatzelsperger]

What this PR changes/adds

Switches to creating the tags and merge commit using plain bash (as opposed to: GH actions)

Why it does that

There were weird, unreproducible and undebuggable "merge conflict" errors in the past. Also, bash scripts are easier to debug and replicate locally.

Further notes

• successful test in my fork: https://github.com/paullatzelsperger/Technology-Aws/actions/runs/10056788484

Linked Issue(s)

Closes # <-- insert Issue number if one exists

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.47%. Comparing base (d177a98) to head (da4d6c8).
Report is 56 commits behind head on main.

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Additional details and impacted files

@@             Coverage Diff              @@
##               main     #382      +/-   ##
============================================
+ Coverage     63.82%   65.47%   +1.65%     
- Complexity        0      113     +113     
============================================
  Files            26       28       +2     
  Lines           633      672      +39     
  Branches         30       32       +2     
============================================
+ Hits            404      440      +36     
+ Misses          222      218       -4     
- Partials          7       14       +7     

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