Chore/multiple fixes ci precommit

[theissenhelen]

fixes/updates:

• correct downstream-ci-hpc workflow call
• ignore pre-commit-config and readthedocs for changelog updates
• updates pre-commit config

adds:

• merge strategy for CHANGELOG.md
• adds CODEOWNERS file

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.83%. Comparing base (af4d9dc) to head (049319a). Report is 11 commits behind head on develop.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #41 +/- ## ======================================== Coverage 99.82% 99.83% ======================================== Files 21 22 +1 Lines 1158 1213 +55 ======================================== + Hits 1156 1211 +55 Misses 2 2 ```

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[JesperDramsch]

Thanks @anaprietonem