fix: mark `FormData` as non-serializable in `Bun`

[kricsleo]

resolves #439

[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 70.00%. Comparing base (27996d3) to head (5fc9a0c). :warning: Report is 73 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #483       +/-   ##
===========================================
+ Coverage   56.86%   70.00%   +13.13%     
===========================================
  Files          16       17        +1     
  Lines         728      530      -198     
  Branches      113      140       +27     
===========================================
- Hits          414      371       -43     
+ Misses        303      148      -155     
  Partials       11       11               

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[utpalgupta-blinkit]

When will this be merged?