make configuration immutable

[ekneg54]

closes #660

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.35%. Comparing base (1ef1b78) to head (8e4bf4b).
Report is 17 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #661      +/-   ##
==========================================
- Coverage   94.44%   94.35%   -0.09%     
==========================================
  Files         147      147              
  Lines        9926    10034     +108     
==========================================
+ Hits         9375     9468      +93     
- Misses        551      566      +15     

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[djkhl]

To my understanding everything looks good and works as expected. The only thing i saw is one unsued import. I don't know if you wanted to add more tests to check for this error.