improve webhook parsing

src/consts.rs

@@ -0,0 +1,3 @@
+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