fix examples

Signed-off-by: Yoshua Wuyts <[email protected]>

Author: yoshuawuyts

examples/cookies.rs

@@ -11,7 +11,7 @@ async fn set_cookie(mut cx: Context<()>) {
     cx.set_cookie(Cookie::new("hello", "world")).unwrap();
 }
 
-async fn remove_cookie(mut cx: Context<()>) {
+async fn remove_cookie(cx: Context<()>) {
     cx.remove_cookie(Cookie::named("hello")).unwrap();
 }