fix(ci): release job 添加 checkout 步骤

gh release create 需要在 git 仓库中运行，缺少 checkout 导致
"fatal: not a git repository" 错误。

Author: skhe

.github/workflows/build-wheels.yml

@@ -74,6 +74,8 @@ jobs:
       contents: write
 
     steps:
+      - uses: actions/checkout@v4
+
       - uses: actions/download-artifact@v4
         with:
           path: dist_fixed