run autoformat

apologies to anyone finding this commit via git blame or log

run the autoformatting by

    pre-commit run --all-files

examples/postgres/hub/jupyterhub_config.py

@@ -8,10 +8,10 @@ c.Authenticator.whitelist = {'ganymede', 'io', 'rhea'}
 
 # These environment variables are automatically supplied by the linked postgres
 # container.
-import os;
+import os
+
 pg_pass = os.getenv('POSTGRES_ENV_JPY_PSQL_PASSWORD')
 pg_host = os.getenv('POSTGRES_PORT_5432_TCP_ADDR')
 c.JupyterHub.db_url = 'postgresql://jupyterhub:{}@{}:5432/jupyterhub'.format(
-    pg_pass,
-    pg_host,
+    pg_pass, pg_host
 )