Fixes #298: Repeatedly appending parent path to flatFiles

[mayank-singh-sikarwar]

Purpose: Fix for appending parent path to CSV file paths in cosmx.py reader module.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.

Project coverage is 49.48%. Comparing base (296d9a5) to head (cb147e2).
Report is 174 commits behind head on main.

Files with missing lines	Patch %	Lines
src/spatialdata_io/readers/cosmx.py	0.00%	6 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #305       +/-   ##
===========================================
+ Coverage   39.16%   49.48%   +10.31%     
===========================================
  Files          26       26               
  Lines        2663     2712       +49     
===========================================
+ Hits         1043     1342      +299     
+ Misses       1620     1370      -250     

Files with missing lines	Coverage Δ
src/spatialdata_io/readers/cosmx.py	18.51% <0.00%> (-0.43%)	⬇️

... and 12 files with indirect coverage changes

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