Check blacksmith formatting in CI

Author: ChrisDenton

.github/workflows/deploy.yml

@@ -18,6 +18,8 @@ jobs:
       - uses: actions/checkout@v3
       - name: Install mdbook
         run: curl -sSL https://github.com/rust-lang/mdBook/releases/download/v0.4.35/mdbook-v0.4.35-x86_64-unknown-linux-gnu.tar.gz | tar -xz
+      - name: Check blacksmith format
+        run: cargo fmt --check --manifest-path=blacksmith/Cargo.toml
       - name: Build book
         run: ./mdbook build
       - name: Deploy book