fix: Turn panic into error when serializing Object types

[stinodego]

These are not supported by design, so it should throw a nice error.

[codecov]

Codecov Report

Attention: Patch coverage is 90.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 80.46%. Comparing base (ad836bd) to head (46e91d1).
Report is 5 commits behind head on main.

Files	Patch %	Lines
crates/polars-core/src/serde/series.rs	66.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17353      +/-   ##
==========================================
- Coverage   80.49%   80.46%   -0.03%     
==========================================
  Files        1483     1483              
  Lines      195010   195122     +112     
  Branches     2781     2781              
==========================================
+ Hits       156972   157012      +40     
- Misses      37527    37599      +72     
  Partials      511      511              

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