Fix JOINS by rerlationships

[CosmoV]

Closes #77

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (7e2514e) 77.09% compared to head (f076c45) 77.28%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #78      +/-   ##
==========================================
+ Coverage   77.09%   77.28%   +0.19%     
==========================================
  Files          40       40              
  Lines        2449     2457       +8     
  Branches      358      359       +1     
==========================================
+ Hits         1888     1899      +11     
+ Misses        489      487       -2     
+ Partials       72       71       -1     

Flag	Coverage Δ
unittests	77.28% <100.00%> (+0.19%)	⬆️

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Files	Coverage Δ
...astapi_jsonapi/data_layers/filtering/sqlalchemy.py	83.63% <100.00%> (+0.45%)	⬆️
fastapi_jsonapi/schema.py	84.84% <100.00%> (+5.16%)	⬆️