Check code style in ci

.github/workflows/rustfmt.yml

@@ -0,0 +1,25 @@
+on: [push, pull_request]
+
+name: rustfmt
+
+jobs:
+  rustfmt:
+    name: rustfmt
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v2
+
+      - name: Install stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+          components: rustfmt
+
+      - name: Run cargo fmt
+        uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check