Fixing Auto CI

[rchiorean]

There were two reasons why AutoCI broke:

1. Since ubuntu-latest changed from 20.04 to 22.04 the python-3.6 no longer works. See this this more details.
2. After pandas 1.5.3 the behaviour of pd.to_datetime changed when given a dataframe. We rely on this behaviour at least in the format_raw mehod in pipeline.py

Please let me know if solutions different from the ones implemented would be preferred.

[codecov[bot]]

Codecov Report

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

Project coverage is 100.00%. Comparing base (1a5113c) to head (ddf5c63). Report is 13 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #111   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files            9         9           
  Lines          415       415           
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  Hits           415       415           

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