🔧 Add in-progress cancellation to CI workflows

[burgholzer]

Per default, GitHub keeps workflows running even if new commits are added to a pull request.
This is wasteful and requires lots of manual cancellations to free up available runners.
This PR adds the corresponding settings to cancel in-progress jobs whenever new commits become available by adding

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

snippets to all the workflow files.

[codecov]

Codecov Report

Merging #76 (66e3cc1) into main (ae0d1e6) will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##            main     #76   +/-   ##
=====================================
  Coverage   91.2%   91.2%           
=====================================
  Files         29      29           
  Lines       1825    1825           
=====================================
  Hits        1666    1666           
  Misses       159     159           

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