Fix: add universal export to root

package.json

@@ -19,7 +19,8 @@
     "lib",
     "conf",
     "LICENSE",
-    "dist"
+    "dist",
+    "universal.js"
   ],
   "publishConfig": {
     "access": "public"

universal.js

@@ -0,0 +1,9 @@
+// Jest (and probably some other runtimes with custom implementations of
+// `require`) doesn't support `exports` in `package.json`, so this file is here
+// to help them load this module. Note that it is also `.js` and not `.cjs` for
+// the same reason - `cjs` files requires to be loaded with an extension, but
+// since Jest doesn't respect `module` outside of ESM mode it still works in
+// this case (and the `require` in _this_ file does specify the extension).
+
+// eslint-disable-next-line no-undef
+module.exports = require("./dist/eslintrc-universal.cjs");