prepare CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,19 @@
+name: CI
+on: [push, pull_request]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          components: rustfmt, clippy
+          override: true
+      - uses: Swatinem/rust-cache@v1
+      - name: rustfmt
+        run: cargo fmt -- --check --color always
+      # - name: clippy
+      #   run: cargo clippy --color always -- -D warnings