Fix hardlink file warning in CI

using new checks in CI outputs the following warning:

```
warning: Failed to hardlink files; falling back to full copy. This may lead to degraded performance.

If the cache and target directories are on different filesystems, hardlinking may not be supported.

If this is intentional, set `export UV_LINK_MODE=copy` or use `--link-mode=copy` to suppress this warning.
```