fix: include types in package.json exports (#321)

Author: joelmukuthu

packages/vite-plugin-windicss/package.json

@@ -19,6 +19,7 @@
   ],
   "exports": {
     ".": {
+      "types": "./dist/index.d.ts",
       "require": "./dist/index.js",
       "import": "./dist/index.mjs"
     },