All warning as errors pytest

[martins0n]

Before submitting (must do checklist)

• Did you read the contribution guide?
• Did you update the docs? We use Numpy format for all the methods and classes.
• Did you write any new necessary tests?
• Did you update the CHANGELOG?

Proposed Changes

Closing issues

[github-actions]

🚀 Deployed on https://deploy-preview-880--etna-docs.netlify.app

[codecov-commenter]

Codecov Report

Merging #880 (9df6aef) into master (c066733) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #880   +/-   ##
=======================================
  Coverage   84.75%   84.75%           
=======================================
  Files         132      132           
  Lines        7473     7473           
=======================================
  Hits         6334     6334           
  Misses       1139     1139           

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