fix: derive Clone for SessionKey

Author: willothy

actix-session/src/storage/session_key.rs

@@ -14,7 +14,7 @@ use derive_more::derive::{Display, From};
 /// let session_key: Result<SessionKey, _> = key.try_into();
 /// assert!(session_key.is_err());
 /// ```
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub struct SessionKey(String);
 
 impl TryFrom<String> for SessionKey {