fix: Fixed BinaryClassificationTrainer

[frgfm]

This PR introduces the following modifications:

• fixes trainer for binary classification when the target is wrongly shaped or doesn't have the good data type
• fixes the evaluation loop of binary classification trainer
• extends unittests

[codecov]

Codecov Report

Merging #227 (1130104) into main (49125c2) will decrease coverage by 0.08%.
The diff coverage is 78.12%.

@@            Coverage Diff             @@
##             main     #227      +/-   ##
==========================================
- Coverage   93.51%   93.43%   -0.09%     
==========================================
  Files          56       56              
  Lines        3132     3136       +4     
==========================================
+ Hits         2929     2930       +1     
- Misses        203      206       +3     

Impacted Files	Coverage Δ
holocron/trainer/classification.py	86.44% <63.15%> (-4.64%)	⬇️
holocron/trainer/core.py	89.57% <100.00%> (+0.30%)	⬆️
holocron/trainer/segmentation.py	100.00% <100.00%> (ø)