[MRG] Make DeepDADAtaset deal with regression masking

[tgnassou]

• Add allow_label_masks in DeepDADataset to deal with regression masking (NaN)
• Add comparison between NaN in the tests
• Fix indentation and whitespace in deep.base.

[codecov]

Codecov Report

❌ Patch coverage is 96.87500% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 96.20%. Comparing base (0215604) to head (3b87611).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #352   +/-   ##
=======================================
  Coverage   96.20%   96.20%           
=======================================
  Files          64       64           
  Lines        7036     7039    +3     
=======================================
+ Hits         6769     6772    +3     
  Misses        267      267           

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