👷 Move build chain to ESM (#4591)

Moving the root of the monorepo to ESM.
This part not being published at all, we don't expect any impacts to our users and can safely flag it as no-op from a versionning point of view.

package.json

@@ -2,6 +2,7 @@
   "private": true,
   "name": "@fast-check/monorepo",
   "description": "Test making sure fast-check expose the right typings",
+  "type": "module",
   "packageManager": "[email protected]",
   "workspaces": [
     ".github/actions/*",