fix: datetime_attribute account for 0 or 1-indexing of the attributes

[madtoinou]

Fixes #2219.

Summary

• datetime_attribute_timeseries() was not taking into account the indexing of the attribute (1 for month, day or week for example), resulting in a shift of the "zeroed" columns
• 0-indexing is enforced for all the encodings (1-indexed attributes are shifted by one)

Other Information

• added some tests

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 93.97%. Comparing base (ccd0d42) to head (ad76339).

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2242      +/-   ##
==========================================
+ Coverage   93.95%   93.97%   +0.02%     
==========================================
  Files         135      135              
  Lines       13501    13499       -2     
==========================================
+ Hits        12685    12686       +1     
+ Misses        816      813       -3     

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