Add lint job to CI (#101)

Signed-off-by: Ondrej Vasko <[email protected]>

.github/workflows/tests.yaml

@@ -2,8 +2,34 @@
 name: Integration tests with Kind and DevStack
 on: [pull_request]
 jobs:
+  lint:
+    name: "Linters (go v${{ matrix.go-version }})"
+    runs-on: ubuntu-20.04
+    strategy:
+      matrix:
+        go-version: [ '1.20' ]
+    steps:
+      - name: Checkout velero-plugin-for-openstack
+        uses: actions/checkout@v3
+      - name: Setup Go ${{ matrix.go-version }}
+        uses: actions/setup-go@v3
+        with:
+          go-version: ${{ matrix.go-version }}
+      - name: Check formatting
+        run: |
+          test -z $(gofmt -l -s ./)
+      - name: Check go vet
+        run: |
+          go vet ./...
+      - name: Verify dependencies
+        run: |
+          go mod verify
+      - name: Check if plugin can be built
+        run: |
+          go build -v .
   unit-test:
     name: "Unit tests (go v${{ matrix.go-version }})"
+    needs: lint
     runs-on: ubuntu-20.04
     strategy:
       matrix: