fix(github): correct pagination log to show last fetched page

Changed stopped_at_page to last_page_fetched (page - 1) since the
logged value was the next page to fetch, not the last one retrieved.

Author: DevanshuNEU

backend/services/github.py

@@ -181,7 +181,7 @@ async def get_all_repos(
                     "GitHub repo pagination stopped at limit",
                     max_pages=max_pages,
                     total_repos_fetched=len(all_repos),
-                    stopped_at_page=page
+                    last_page_fetched=page - 1
                 )
                 break
         return all_repos