Hydrology Basin Aggregation Clean

[Wegatriespython]

Cleaned up and refactored hydro_agg_basin.py to a be jupyter notebook

Old file was in a poor condition was hard to decipher and had many errors.

1. Datetime issues, there was no month to group on

 .groupby(["month"]

2. val_2020 calculation
   Used 16 years instead of 12 months to calculate 2020 values.

qtot_2p6_gfdl_avg = qtot_2p6_gfdl[pd.date_range("2015-01-01", periods=192, freq="M")]
qtot_7p0_gfdl_avg = qtot_7p0_gfdl[pd.date_range("2015-01-01", periods=192, freq="M")]

val_2020 = (
    qtot_7p0_gfdl_avg.T.groupby(["month"]).mean()
    + qtot_2p6_gfdl_avg.T.groupby(["month"]).mean()
) / 2

3. Loop was overwriting all outputs to the final 5 year block in bias_correction

    for year in np.arange(2020, 2105, 5):
          df_{name}
          
   return df_{name}

How to review

Read the notebook.
Clarify any issues

PR checklist

• Continuous integration checks all ✅
• Add or expand tests; coverage checks both ✅
• Add, expand, or update documentation.
• Update doc/whatsnew.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.0%. Comparing base (c8ab04d) to head (2f736a0).

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #357   +/-   ##
=====================================
  Coverage   72.0%   72.0%           
=====================================
  Files        243     243           
  Lines      19451   19451           
=====================================
  Hits       14011   14011           
  Misses      5440    5440           

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