Add missing type export declaration (#11)

This will allow people to use this package together with the new
moduleResolution: "bundler" option enabled, which was added
in TypeScript 5.0.

Otherwise type declarations are entirely missing.

package.json

@@ -17,7 +17,8 @@
   "source": "src/index.ts",
   "exports": {
     "require": "./dist/index.cjs",
-    "default": "./dist/index.esm.js"
+    "default": "./dist/index.esm.js",
+    "types": "./dist/index.d.ts"
   },
   "types": "./dist/index.d.ts",
   "main": "./dist/index.cjs",
@@ -62,4 +63,4 @@
     "update",
     "change"
   ]
-}
+}