cmd/git(fix[Git.clone]): Fix separate_git_dir repr quoting issue

why: Using !r (repr) incorrectly added quotes around the path, causing
git to fail with "unknown option: --separate-git-dir='/path/to/dir'".
what:
- Change {separate_git_dir!r} to {separate_git_dir!s} to match init()

Author: tony

src/libvcs/cmd/git.py

@@ -353,7 +353,7 @@ def clone(
         if template is not None:
             local_flags.append(f"--template={template}")
         if separate_git_dir is not None:
-            local_flags.append(f"--separate-git-dir={separate_git_dir!r}")
+            local_flags.append(f"--separate-git-dir={separate_git_dir!s}")
         if (_filter := kwargs.pop("_filter", None)) is not None:
             local_flags.append(f"--filter={_filter}")
         if depth is not None: