ci: add rustfmt check

Signed-off-by: Nick Spinale <[email protected]>

.github/workflows/pr.yml

@@ -51,3 +51,19 @@ jobs:
           key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
       - name: Run Clippy
         run: cd tool/microkit && cargo clippy --all-targets --all-features
+
+  rustfmt_check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/cache@v3
+        with:
+          path: |
+            ~/.cargo/bin/
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+            target/
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+      - name: Run rustfmt
+        run: cd tool/microkit && cargo fmt --check