Actually add lint job to CI

.github/workflows/check.yml

@@ -0,0 +1,35 @@
+name: Lint
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  lint:
+    name: Lint
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up Go
+        uses: actions/setup-go@v3
+        with:
+          go-version: 1.20.x
+        id: go
+
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: golangci-lint
+        uses: golangci/golangci-lint-action@v3
+        with:
+          version: v1.51
+          args: --verbose --timeout 5m
+
+      - name: Check go.mod/go.sum
+        run: |
+          echo "check if go.mod and go.sum are up to date"
+          go mod tidy
+          git diff --exit-code go.mod go.sum