Bugfix/progressbar pickling

[justusschock]

What does this PR do?

Fixes
Progressbar became unpickleable after predict.

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[pep8speaks]

Hello @justusschock! Thanks for updating this PR.

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2021-05-19 10:58:51 UTC

[codecov]

Codecov Report

Merging #7609 (ac37895) into master (20f6337) will decrease coverage by 48%.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           master   #7609     +/-   ##
========================================
- Coverage      92%     44%    -48%     
========================================
  Files         197     197             
  Lines       12878   12875      -3     
========================================
- Hits        11899    5656   -6243     
- Misses        979    7219   +6240