fix: Fixes exports to correctly export test utils (#921)

This change slightly adjusts the exports in this repo's package.json in order to expose the required test utilities to consumers.

While it works to provide the alias within 529bc1f, it's slightly confusing to consumers who expect the export to map to a real path on disc.

Relates to #920 and tweaks 529bc1f to use correct path.

package.json

@@ -38,7 +38,7 @@
   "type": "module",
   "exports": {
     ".": "./lib/index.js",
-    "./test/util.js": "./test/util/index.js"
+    "./test/util/index.js": "./test/util/index.js"
   },
   "files": [
     "bin",