fix: Fix types prop in package.json

Author: kevin-greene-ck

package.json

@@ -3,7 +3,7 @@
   "version": "0.0.1",
   "description": "A dynamic feature flags library for Node.js",
   "main": "dist/main/index.js",
-  "types": "dist/main/index.ts",
+  "types": "dist/main/index.d.ts",
   "files": [
     "dist/main"
   ],