Improve local URL detection

IPv4 loopback is 127/8, so treat entire range as local.

Author: Roy-Orbison

jupyter_server/serverapp.py

@@ -2377,7 +2377,7 @@ def local_url(self) -> str:
         parts = self._get_urlparts(include_token=True)
         # Update with custom pieces.
         if not self.sock:
-            localhost = "[::1]" if ":" in self.ip else "127.0.0.1"
+            localhost = "[::1]" if ":" in self.ip else self.ip if self.ip.startswith("127.") else "127.0.0.1"
             parts = parts._replace(netloc=f"{localhost}:{self.port}")
         return parts.geturl()