Fix types definition (#34)

Author: balthild

package.json

@@ -7,6 +7,7 @@
   "types": "types/index.d.ts",
   "type": "module",
   "exports": {
+    "types": "./types/index.d.ts",
     "import": "./dist/index.mjs",
     "require": "./dist/index.cjs"
   },