chore: Improve export field in package.json

Author: leo91000

package.json

@@ -25,7 +25,8 @@
   "exports": {
     ".": {
       "import": "./dist/index.mjs",
-      "require": "./dist/index.cjs"
+      "require": "./dist/index.cjs",
+      "types": "./dist/index.d.ts"
     }
   },
   "main": "dist/index.cjs",