Update Go workflow: include lint action

.github/workflows/go.yml

@@ -1,5 +1,6 @@
 # This workflow will build a golang project
 # For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-go
+# Adapted from https://github.com/RedTeamPentesting/adauth/blob/main/.github/workflows/check.yml :)
 
 name: Go
 
@@ -20,6 +21,18 @@ jobs:
         with:
           go-version: ${{ matrix.go-version }}
 
+      - name: Lint
+        uses: golangci/golangci-lint-action@v3
+        with:
+          version: v1.64
+          args: --verbose --timeout 5m
+
+      - name: Check go.mod
+        run: |
+          echo "check if go.mod is up to date"
+          go mod tidy
+          git diff --exit-code go.mod
+
       - name: Build
         run: go build -v ./...