style(oauth_setup): normalize string quoting in _sanitize_input

* Replace single quotes with double quotes in `rstrip("\r\n")` for consistent quoting style.
* Add minor formatting cleanup (extra blank line) for readability.
* No functional changes.

Author: njoshi-conga

src/mcp_atlassian/utils/oauth_setup.py

@@ -41,9 +41,10 @@ def _sanitize_input(user_input: str) -> str:
         return user_input
     # Remove leading/trailing whitespace and various line endings
     # Handle Windows (\r\n), Unix (\n), and Mac (\r) line endings
-    sanitized = user_input.strip().rstrip('\r\n').strip()
+    sanitized = user_input.strip().rstrip("\r\n").strip()
     return sanitized
 
+
 class CallbackHandler(http.server.BaseHTTPRequestHandler):
     """HTTP request handler for OAuth callback."""