chore: add package.json to export map (#8838)

Author: haoqunjiang

packages/vite/package.json

@@ -20,7 +20,8 @@
     "./client": {
       "types": "./client.d.ts"
     },
-    "./dist/client/*": "./dist/client/*"
+    "./dist/client/*": "./dist/client/*",
+    "./package.json": "./package.json"
   },
   "files": [
     "bin",