CI: Check formatting

.github/workflows/fmt.yml

@@ -0,0 +1,37 @@
+name: Formatting
+
+on:
+  push:
+    branches: [ main ]
+    paths:
+      - "src/**/*.rs"
+      - "Cargo.toml"
+      - ".github/workflows/fmt.yml"
+  pull_request:
+    branches: [ main ]
+    paths:
+      - "src/**/*.rs"
+      - "Cargo.toml"
+      - ".github/workflows/fmt.yml"
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  rustfmt:
+    name: Verify code formatting
+    runs-on: ubuntu-latest
+    steps:
+      - name: VCS Checkout
+        uses: actions/checkout@v3
+      - name: Install rust (latest stable)
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          override: true
+          components: rustfmt
+      - name: Run cargo fmt
+        uses: actions-rs/cargo@v1
+        with:
+          command: "fmt"
+          args: "--all -- --check"