fix：修复github action 后端检测失败问题

Author: mingjia1

.github/workflows/ci.yml

@@ -15,7 +15,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v5
         with:
-          go-version: '1.21'
+          go-version-file: ./platform-backend/go.mod
 
       - name: Go test
         working-directory: ./platform-backend
@@ -55,7 +55,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v5
         with:
-          go-version: '1.21'
+          go-version-file: ./agent/go.mod
 
       - name: Go test
         working-directory: ./agent