fix stl10 datamodule

[ananyahjha93]

What does this PR do?

creates uniformity between labeled data split and labeled data split within mixed data loader.

Fixes # (issue)

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[codecov]

Codecov Report

Merging #369 (0f12182) into master (6409e84) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #369   +/-   ##
=======================================
  Coverage   82.00%   82.00%           
=======================================
  Files         100      100           
  Lines        5639     5639           
=======================================
  Hits         4624     4624           
  Misses       1015     1015           

Flag	Coverage Δ
cpu	24.55% <ø> (ø)
pytest	24.55% <ø> (ø)
unittests	81.25% <ø> (ø)

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