Fix CI Go module issue: use regular module mode with explicit env vars

- Remove vendor mode approach, use regular Go modules
- Add GOPROXY and GOSUMDB environment variables
- Explicitly set GO111MODULE=on for all Go commands
- Remove unnecessary vendor step

.gitea/workflows/ci.yml

@@ -67,6 +67,8 @@ jobs:
         run: go mod download
         env:
           GO111MODULE: on
+          GOPROXY: https://proxy.golang.org,direct
+          GOSUMDB: sum.golang.org
       - name: Tidy and verify modules
         working-directory: bugulma/backend
         run: |
@@ -74,19 +76,22 @@ jobs:
           go mod verify
         env:
           GO111MODULE: on
-      - name: Vendor dependencies
-        working-directory: bugulma/backend
-        run: go mod vendor
-        env:
-          GO111MODULE: on
+          GOPROXY: https://proxy.golang.org,direct
+          GOSUMDB: sum.golang.org
       - name: Vet
         working-directory: bugulma/backend
-        run: go vet -mod=vendor ./...
+        run: go vet ./...
         env:
           GO111MODULE: on
+          GOPROXY: https://proxy.golang.org,direct
+          GOSUMDB: sum.golang.org
       - name: Test
         working-directory: bugulma/backend
-        run: go test -v -race -coverprofile=coverage.out -mod=vendor ./...
+        run: go test -v -race -coverprofile=coverage.out ./...
+        env:
+          GO111MODULE: on
+          GOPROXY: https://proxy.golang.org,direct
+          GOSUMDB: sum.golang.org
       - name: Coverage
         working-directory: bugulma/backend
         run: go tool cover -html=coverage.out -o coverage.html