Fix/pydantic 2 pytest

[clausmichele]

The tests were failing, due to the change in syntax needed by Pydantic>2.
Now all the tests are passing except one about machine learning, @ValentinaHutter could you check please?

Edit: Here the tests are all passing, probably the one that failed is due to some different library version on my side.
Edit 2: I also added again the aggregate_spatial, which are passing if we don't use the latest xarray version.
Edit 3: I also fixed the pandas version to >=2.0.0, which solves this issue #184

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.77%. Comparing base (d02965c) to head (64163bd).
Report is 2 commits behind head on main.

❗ Current head 64163bd differs from pull request most recent head 3a509d0

Please upload reports for the commit 3a509d0 to get more accurate results.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #259      +/-   ##
==========================================
+ Coverage   80.58%   82.77%   +2.18%     
==========================================
  Files          29       29              
  Lines        1638     1643       +5     
==========================================
+ Hits         1320     1360      +40     
+ Misses        318      283      -35     

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