CI: improve workflow (checkout v3, setup-go v4, cache, fmt/vet)

.gitea/workflows/ci.yml

@@ -7,11 +7,27 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Set up Go
-        uses: actions/setup-go@v2
+        uses: actions/setup-go@v4
         with:
           go-version: '1.20'
+      - name: Cache Go modules
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cache/go-build
+            ~/go/pkg/mod
+          key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+          restore-keys: |
+            ${{ runner.os }}-go-
+      - name: Tidy modules
+        run: go mod tidy
+      - name: Format check
+        run: |
+          gofmt_out=$(gofmt -l . | wc -l); if [ "$gofmt_out" -ne "0" ]; then echo "gofmt needs to be run"; gofmt -w .; exit 1; fi
+      - name: Vet
+        run: go vet ./...
       - name: Build
         run: make build
       - name: Test