Function find_manage_py_root 

pub fn find_manage_py_root(scan_root: &Path) -> Option<PathBuf>

Search depth 1 and depth 2 subdirectories of scan_root for a manage.py file.

Returns the first subdirectory that contains manage.py, or None if manage.py exists at scan_root itself (already covered by canonical_root) or no subdirectory contains manage.py.