Export as ESM

[blakeembrey]

Discussed with TC, the plan is that all utilities will become ESM unless there's a valuable reason to release for Express 5 specifically. Since the current version is used without any real maintenance overhead, I think we should move to ESM for the next major release.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (1ba386f) to head (1139f1d).

Additional details and impacted files

@@            Coverage Diff            @@
##            master       #99   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines           55        55           
  Branches        20        20           
=========================================
  Hits            55        55           

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[Phillip9587]

LGTM!