Use nightly toolchain when checking formatting.

Author: conqp

.github/workflows/rust.yaml

@@ -18,7 +18,7 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - name: Check formatting
-        run: cargo fmt --check
+        run: cargo +nightly fmt --check
       - name: Lint with clippy
         run: cargo clippy --all-features -- -A clippy::multiple_crate_versions -D warnings
       - name: Run tests