Remove soon to be deprecated jsonschema.RefResolver

[h-mayorquin]

Should close #1048.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.60%. Comparing base (cbf68d4) to head (0cd207e).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1133      +/-   ##
==========================================
+ Coverage   90.55%   90.60%   +0.04%     
==========================================
  Files         129      129              
  Lines        8187     8177      -10     
==========================================
- Hits         7414     7409       -5     
+ Misses        773      768       -5     

Flag	Coverage Δ
unittests	90.60% <100.00%> (+0.04%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...on_specification/_yaml_conversion_specification.py	97.26% <100.00%> (+0.11%)	⬆️