Create a metaclass for Singleton's and remove pysingleton

[alexandrehassan]

I don't know if this is where you want the singleton Meta class to be (or the tests). This completely removes the pysingleton library. Closes #471 .

Added quick tests to prove that it replaces the old singleton.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.44%. Comparing base (e9d7a8b) to head (eed81d7).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #492      +/-   ##
==========================================
+ Coverage   87.41%   87.44%   +0.02%     
==========================================
  Files          38       38              
  Lines        2329     2334       +5     
==========================================
+ Hits         2036     2041       +5     
  Misses        293      293              

Flag	Coverage Δ
unittests	87.44% <100.00%> (+0.02%)	⬆️

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[fliiiix]

location is fine a bit more comments how that works and how to use it here would be nice

[fliiiix]

Can you rebase and make sure these 2 commits are not part of this mr?