ci: Use nix for the format check step

Author: nicholasbishop

.github/workflows/rust.yml

@@ -88,16 +88,10 @@ jobs:
       - name: Checkout sources
         uses: actions/checkout@v4
       - uses: Swatinem/rust-cache@v2
-      - name: Install yamlfmt
-        env:
-          YFV: "0.13.0"
-          HASH: "043e96d754a8afa4f4c5c13ffb2f3e50c6be5a70bf53292d3025abc0b42fe4ae"
-        run: |
-          curl -L --fail --output /tmp/yamlfmt.tar.xz https://github.com/google/yamlfmt/releases/download/v${YFV}/yamlfmt_${YFV}_Linux_x86_64.tar.gz
-          echo "${HASH} /tmp/yamlfmt.tar.xz" | sha256sum --check
-          tar xf /tmp/yamlfmt.tar.xz -C /usr/local/bin yamlfmt
+      - name: Install nix
+        uses: cachix/install-nix-action@v27
       - name: Check formatting
-        run: cargo xtask fmt --check
+        run: nix-shell --run "cargo xtask fmt --check"
       - name: Run clippy
         run: |
           rustup component add clippy