docs: rm unused import statement from refresh token rotation page example code (#12804)

chore(docs/refresh-token-rotation): deleted unused/out-of-place import statement

For Next.js, there was a leftover import statement in the server-side code from the client-side code. I deleted the leftover import statement because useEffect is out of place in the server side, and thus was left unused in the server-side code.

Author: karthikappiah

docs/pages/guides/refresh-token-rotation.mdx

@@ -241,7 +241,6 @@ If the token refresh was unsuccesful, we can force a re-authentication.
 <Code.Next>
 
 ```tsx filename="app/dashboard/page.tsx"
-import { useEffect } from "react"
 import { auth, signIn } from "@/auth"
 
 export default async function Page() {