Fix GoToEvent query param

[elio2t]

Fixes #188

Not proud of as Record<string, string> but it's the best solution I found to keep ts happy even though URLSearchParams works fine with numbers 🤷:

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.01%. Comparing base (16abe6a) to head (8641241).
Report is 31 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #363      +/-   ##
==========================================
+ Coverage   95.68%   97.01%   +1.33%     
==========================================
  Files          14       15       +1     
  Lines         950     1173     +223     
==========================================
+ Hits          909     1138     +229     
+ Misses         41       35       -6     

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