fix: extract PR number correctly to fix pull request comments URL

aider_gitea/gitea_client.py

@@ -178,6 +178,7 @@ class GiteaClient:
         """
         Fetch comments for a pull request.
         """
+        pr_number = str(pr_number).rstrip('/').split('/')[-1]
         url = f'{self.gitea_url}/repos/{owner}/{repo}/pulls/{pr_number}/comments'
         response = self.session.get(url)
         response.raise_for_status()