compact debug log into single line

replace pformat/pprint with json.dumps

dockerspawner/dockerspawner.py

@@ -3,13 +3,13 @@
 """
 import asyncio
 import inspect
+import json
 import os
 import string
 import warnings
 from concurrent.futures import ThreadPoolExecutor
 from functools import partial
 from io import BytesIO
-from pprint import pformat
 from tarfile import TarFile, TarInfo
 from textwrap import dedent, indent
 from urllib.parse import urlparse
@@ -1010,7 +1010,7 @@ async def poll(self):
 
         container_state = container["State"]
         self.log.debug(
-            "Container %s status: %s", self.container_id[:7], pformat(container_state)
+            "Container %s status: %s", self.container_id[:7], json.dumps(container_state, ensure_ascii=False)
         )
 
         if container_state["Running"]: