Fix formatting check

`cargo fmt` cannot see modules declared using macros.

.github/workflows/ci.yml

@@ -38,7 +38,7 @@ jobs:
     - name: Install Rust
       run: rustup update stable && rustup default stable
     - name: Check formatting
-      run: cargo fmt --all -- --check
+      run: rustfmt --check --edition 2021 $(git ls-files '*.rs')
 
   # This represents the minimum Rust version supported by
   # Bytes. Updating this should be done in a dedicated PR.