使checkout action克隆指定分支; 统一代码缩进

.github/workflows/alpha.yml

@@ -66,6 +66,8 @@ jobs:
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
+        with:
+          ref: ${{ github.ref_name }}
 
       - name: 构建Java环境
         uses: actions/setup-java@v3
@@ -132,7 +134,9 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.ref_name }}
 
       - name: 安装Flutter
         if: steps.cache-flutter.outputs.cache-hit != 'true'