updates retrieve_feature_id to ignore case

[azneto]

This pull request addresses issue #...

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[codecov-commenter]

Codecov Report

Merging #313 (55b5084) into master (d94869c) will decrease coverage by 0.03%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master     #313      +/-   ##
==========================================
- Coverage   69.21%   69.17%   -0.04%     
==========================================
  Files          30       30              
  Lines        4028     4033       +5     
  Branches      228      229       +1     
==========================================
+ Hits         2788     2790       +2     
- Misses       1182     1184       +2     
- Partials       58       59       +1     

Impacted Files	Coverage Δ
machado/loaders/common.py	69.47% <50.00%> (-1.64%)	⬇️

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