adds option to use pygt3x to read gt3x files

[Trybnetic]

This PR adds the option to use Pygt3x to read GT3X files. It includes the following changes:

• adds option to use pygt3x
• adds test data
• adds test to ensure correct behavior

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 5 lines in your changes missing coverage. Please review.

Project coverage is 71.45%. Comparing base (44d494d) to head (9f68a45).

Files with missing lines	Patch %	Lines
paat/io.py	66.66%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #29      +/-   ##
==========================================
- Coverage   72.02%   71.45%   -0.57%     
==========================================
  Files           8        8              
  Lines         579      585       +6     
==========================================
+ Hits          417      418       +1     
- Misses        162      167       +5     

Flag	Coverage Δ
unittests	71.45% <66.66%> (-0.57%)	⬇️

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