chore: update to tokio-serde 0.9

[tottoto]

Updates to tokio-serde 0.9.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.04%. Comparing base (9f6cba4) to head (072a43d).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2585      +/-   ##
==========================================
+ Coverage   72.03%   72.04%   +0.01%     
==========================================
  Files          66       66              
  Lines       36953    36953              
==========================================
+ Hits        26619    26623       +4     
+ Misses      10334    10330       -4     

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