更新代码检出步骤和工作区验证提示信息

.gitea/workflows/package.yml

@@ -19,7 +19,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: https://gitea.waternetwork.cn/actions/checkout@v4
         with:
           fetch-depth: 1
 
@@ -132,7 +132,7 @@ jobs:
       - name: Validate workspace
         run: |
           if [ ! -f ./Dockerfile ]; then
-            echo "Dockerfile not found in workspace. Checkout is disabled, so the runner must provide repository files before this job starts."
+            echo "Dockerfile not found in workspace. Repository checkout may have failed or produced an unexpected workspace."
             exit 1
           fi