install rustfmt

Author: liamkinne

.github/workflows/ci.yaml

@@ -18,6 +18,8 @@ jobs:
         with:
           targets: thumbv7em-none-eabihf
           components: rustfmt
+      - name: Install rustfmt
+        run: rustup component add rustfmt
       - name: Check format
         run: cargo fmt --all -- --check