fix: export types (#22)

Author: treins

package.json

@@ -20,7 +20,8 @@
   "exports": {
     ".": {
       "require": "./dist/index.js",
-      "import": "./dist/index.mjs"
+      "import": "./dist/index.mjs",
+      "types": "./dist/index.d.ts"
     }
   },
   "main": "./dist/index.js",