fix: apply polymorphic to Dataset for serde

[wolf4ood]

What this PR changes/adds

Fixes serialization/deserialization of Catalog by applying Polymorphic to Dataset

Why it does that

bug fix

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.88%. Comparing base (7f20ba5) to head (22777d7).
Report is 357 commits behind head on main.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4362      +/-   ##
==========================================
+ Coverage   71.74%   74.88%   +3.14%     
==========================================
  Files         919     1063     +144     
  Lines       18457    21323    +2866     
  Branches     1037     1169     +132     
==========================================
+ Hits        13242    15968    +2726     
- Misses       4756     4832      +76     
- Partials      459      523      +64     

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