Chore: use CommonJS modules for dist

[katspaugh]

#96 didn't work with web-core, it wants CommonJS modules.

I've tested it by copying the dist folder to web-core's node_modules.

[github-actions]

ESLint Summary View Full Report

Annotations are provided inline on the Files Changed tab. You can also see all annotations that were generated on the annotations page.

Type	Occurrences	Fixable
Errors	0	0
Warnings	0	0
Ignored	0	N/A

• Result: ✅ success
• Annotations: 0 total

---

^{Report generated by eslint-plus-action}