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[znicholls]

Description

Checklist

Please confirm that this pull request has done the following:

• Tests added
• Documentation added (where applicable)
• Changelog item added to changelog/

[codecov]

Codecov Report

❌ Patch coverage is 94.44444% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 97.31%. Comparing base (0022bed) to head (67a97d6).
⚠️ Report is 11 commits behind head on main.

Files with missing lines	Patch %	Lines
src/pandas_openscm/grouping.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #37      +/-   ##
==========================================
+ Coverage   97.29%   97.31%   +0.02%     
==========================================
  Files          31       31              
  Lines        1479     1492      +13     
  Branches      164      164              
==========================================
+ Hits         1439     1452      +13     
  Misses         23       23              
  Partials       17       17              

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