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 :white_check_mark:

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

```diff @@ 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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