fix(ci): setup-python with 改用 block 语法，修复 flow mapping 内嵌表达式导致 YAML 解析失败

Author: Zhugy-8086

.github/workflows/ci.yml

@@ -20,7 +20,8 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-python@v5
-        with: { python-version: ${{ matrix.python-version }} }
+        with:
+          python-version: ${{ matrix.python-version }}
       - name: Cache pip
         uses: actions/cache@v4
         with: