Potential fix for pull request finding 'Variable defined multiple times'

Co-authored-by: Copilot Autofix powered by AI <223894421+github-code-quality[bot]@users.noreply.github.com>

Author: mnriem

src/specify_cli/extensions.py

@@ -2159,7 +2159,6 @@ def download_extension(self, extension_id: str, target_dir: Optional[Path] = Non
         # Detect archive format from URL; resolve via Content-Type when needed.
         # `final_url` may differ from `download_url` if the server redirects.
         archive_fmt = detect_archive_format(download_url)
-        final_url = download_url
 
         # Download the archive
         try: