Update server.py

Author: chi2liu

src/mcp/server/fastmcp/server.py

@@ -770,7 +770,7 @@ async def sse_endpoint(request: Request) -> Response:
     def streamable_http_app(self) -> Starlette:
         """Return an instance of the StreamableHTTP server app."""
         from starlette.middleware import Middleware
-        from starlette.routing import Route
+        from starlette.routing import Mount
 
         # Create session manager on first call (lazy initialization)
         if self._session_manager is None: