deprecated name warn() -> warning()

notebook/services/contents/filemanager.py

@@ -240,13 +240,13 @@ class FileContentsManager(FileManagerMixin, ContentsManager):
             # https://github.com/jupyter/notebook/issues/2539
             # https://github.com/jupyter/notebook/issues/2757
             # Use the Unix epoch as a fallback so we don't crash.
-            self.log.warn('Invalid mtime %s for %s', info.st_mtime, os_path)
+            self.log.warning('Invalid mtime %s for %s', info.st_mtime, os_path)
             last_modified = datetime(1970, 1, 1, 0, 0, tzinfo=tz.UTC)
 
         try:
             created = tz.utcfromtimestamp(info.st_ctime)
         except (ValueError, OSError):  # See above
-            self.log.warn('Invalid ctime %s for %s', info.st_ctime, os_path)
+            self.log.warning('Invalid ctime %s for %s', info.st_ctime, os_path)
             created = datetime(1970, 1, 1, 0, 0, tzinfo=tz.UTC)
 
         # Create the base model.