chore: Fix mocha in Node v22+

Author: rschristian

package.json

@@ -4,6 +4,7 @@
   "version": "10.25.4",
   "private": false,
   "description": "Fast 3kb React-compatible Virtual DOM library.",
+  "type": "commonjs",
   "main": "dist/preact.js",
   "module": "dist/preact.module.js",
   "umd:main": "dist/preact.umd.js",