fix: Fixes exports to correctly export test utils

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 release-it@529bc1f, it's slightly confusing to consumers who expect the export to map to a real path on disc.

Relates to release-it#920 and tweaks release-it@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",