Fix type hint

Author: chriszarate

src/wp-includes/collaboration/class-wp-sync-post-meta-storage.php

@@ -123,7 +123,7 @@ public function get_awareness_state( string $room ): array {
 	 * @param string            $room      Room identifier.
 	 * @param array<int, mixed> $awareness Serializable awareness state.
 	 */
-	public function set_awareness_state( string $room, mixed $awareness ): void {
+	public function set_awareness_state( string $room, array $awareness ): void {
 		$post_id  = $this->get_storage_post_id();
 		$meta_key = $this->get_awareness_meta_key( $room );