add fix for mouse tra annotation problem

[zktuong]

Closes #376

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 84.04%. Comparing base (48c1a02) to head (7e68083).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #377      +/-   ##
==========================================
- Coverage   84.05%   84.04%   -0.01%     
==========================================
  Files          52       52              
  Lines        9139     9141       +2     
==========================================
+ Hits         7682     7683       +1     
- Misses       1457     1458       +1     

Flag	Coverage Δ
unittests	84.04% <75.00%> (-0.01%)	⬇️

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Files	Coverage Δ
dandelion/preprocessing/_preprocessing.py	69.89% <ø> (ø)
dandelion/preprocessing/external/_preprocessing.py	74.13% <75.00%> (-0.29%)	⬇️