fix: Resolve failing tests after pydantic V2 merge

[frascuchon]

Description

This PR resolves failing tests after pydantic V2 upgrade:

• Changes the expected error details
• Catch TypeError exception inside validator to resolve as a 422 status response

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested

Checklist

• I added relevant documentation
• I followed the style guidelines of this project
• I did a self-review of my code
• I made corresponding changes to the documentation
• I confirm My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I have added relevant notes to the CHANGELOG.md file (See https://keepachangelog.com/)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.79%. Comparing base (f346a84) to head (f7846ae).
Report is 32 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #5700      +/-   ##
===========================================
+ Coverage    91.08%   91.79%   +0.70%     
===========================================
  Files          150      161      +11     
  Lines         6250     6738     +488     
===========================================
+ Hits          5693     6185     +492     
+ Misses         557      553       -4     

Flag	Coverage Δ
argilla-server	91.79% <100.00%> (+0.70%)	⬆️

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