Stop rustfmt from trying to find and format submodules

Author: svix-jplatte

src/util.rs

@@ -29,7 +29,17 @@ pub(crate) fn run_formatter(path: &Utf8Path) {
     };
 
     let (formatter, args) = match file_ext {
-        "rs" => ("rustfmt", ["+nightly", "--edition", "2021"].as_slice()),
+        "rs" => (
+            "rustfmt",
+            [
+                "+nightly",
+                "--unstable-features",
+                "--skip-children",
+                "--edition",
+                "2021",
+            ]
+            .as_slice(),
+        ),
         "go" => ("gofmt", ["-w"].as_slice()),
         "kt" => ("ktfmt", ["--kotlinlang-style"].as_slice()),
         _ => {