fix(testing): support canary timer return types

[tomas-zijdemans]

On Deno canary we are using newer built-in type declarations plus TypeScript 6. In that environment, global setTimeout() / setInterval() are typed as returning Timeout, not number.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.61%. Comparing base (cd03740) to head (27f2766).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7127   +/-   ##
=======================================
  Coverage   94.61%   94.61%           
=======================================
  Files         634      634           
  Lines       51799    51801    +2     
  Branches     9329     9329           
=======================================
+ Hits        49009    49011    +2     
  Misses       2216     2216           
  Partials      574      574           

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[bartlomieju]

Thanks!