create CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,40 @@
+name: CI
+
+on: [push, pull_request]
+
+jobs:
+  format:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-go@v3
+        with:
+          go-version: 1.20
+      - name: Check diff between gofmt and code
+        run: diff <(gofmt -d .) <(echo -n)
+
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go-version: [1.18, 1.19, 1.20]
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-go@v3
+        with:
+          go-version: ${{ matrix.go-version }}
+      - name: Run tests
+        run: go test -v -race ./...
+
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-go@v4
+        with:
+          go-version: 1.20
+          cache: false
+      - name: golangci-lint
+        uses: golangci/golangci-lint-action@v3
+        with:
+          version: v1.53