Fix signature of AutoML classes to not change

[Mr-Geekman]

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

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Codecov Report

Merging #1300 (bed820f) into master (d71274d) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

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@@            Coverage Diff             @@
##           master    #1300      +/-   ##
==========================================
- Coverage   88.79%   88.79%   -0.01%     
==========================================
  Files         193      193              
  Lines       11751    11750       -1     
==========================================
- Hits        10434    10433       -1     
  Misses       1317     1317              

Impacted Files	Coverage Δ
etna/auto/auto.py	95.69% <100.00%> (-0.02%)	⬇️

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