Add gitea download git diff limit

src/consts.rs

@@ -1,6 +1,8 @@
 pub const GITEA_SIG_HEADER_NAME: &str = "x-gitea-signature";
 pub const GITEA_EVENT_TYPE_HEADER_NAME: &str = "x-gitea-event-type";
+
 pub const MAX_WEBHOOK_BODY_SIZE: usize = 1024 * 1024; // 1 MiB
+pub const MAX_DIFF_SIZE: usize = 1024 * 1024; // 1 MiB
 
 pub const BOT_PROCESS_MSG: &str = "
     Review in progress with the model \"{model}\"...