[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

nbviewer/app.py

@@ -460,8 +460,10 @@ def default_endpoint(self):
             default_host, default_port = url.hostname, url.port
 
             if default_port < 1 or default_port > 65535:
-                self.log.error("Received invalid port number %d through JUPYTERHUB_SERVICE_URL. "
-                               "Defaulting to 5000 instead.")
+                self.log.error(
+                    "Received invalid port number %d through JUPYTERHUB_SERVICE_URL. "
+                    "Defaulting to 5000 instead."
+                )
                 default_port = 5000
         else:
             default_host, default_port = "0.0.0.0", 5000