add github workflows

.github/workflows/reviewdog.yml

@@ -0,0 +1,21 @@
+name: reviewdog
+
+on:
+  pull_request:
+    branches: [ "master" ]
+
+jobs:
+  check:
+
+    runs-on: windows-latest
+
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Format code
+      run: cargo fmt
+
+    - name: suggester / rustfmt
+      uses: reviewdog/action-suggester@v1
+      with:
+        tool_name: rustfmt