utoipa-axum: Allow trailing comma in routes!() macro

Once the `routes!()` invocation contains more than a couple of routes, it is likely that each route will be on its own line. Currently, the macro does not support trailing commas, which causes the git diff when adding a new route to be unnecessarily large. With this change trailing commas are supported, which shrinks the diff down to a single-line change.

utoipa-axum/src/lib.rs

@@ -123,7 +123,7 @@ pub use paste::paste;
 /// ```
 #[macro_export]
 macro_rules! routes {
-    ( $handler:path $(, $tail:path)* ) => {
+    ( $handler:path $(, $tail:path)* $(,)? ) => {
         {
             use $crate::PathItemExt;
             let mut paths = utoipa::openapi::path::Paths::new();
@@ -252,6 +252,12 @@ mod tests {
         let _ = router.get_openapi();
     }
 
+    #[test]
+    fn routes_with_trailing_comma_compiles() {
+        let _: OpenApiRouter = OpenApiRouter::new()
+            .routes(routes!(get_user, post_user, delete_user,));
+    }
+
     #[test]
     fn openapi_router_with_openapi() {
         use utoipa::OpenApi;