ci: simplify rustfmt invocation (RustPython#5064)

Author: calebcartwright

.github/workflows/ci.yaml

@@ -308,7 +308,7 @@ jobs:
         with:
             components: rustfmt, clippy
       - name: run rustfmt
-        run: cargo fmt --all -- --check
+        run: cargo fmt --check
       - name: run clippy on wasm
         run: cargo clippy --manifest-path=wasm/lib/Cargo.toml -- -Dwarnings
       - uses: actions/setup-python@v4