fix: close did not work when deleting due to missing import (#4)

Author: maartenbreddels

comm/base_comm.py

@@ -92,6 +92,7 @@ def open(self, data=None, metadata=None, buffers=None):
 
     def close(self, data=None, metadata=None, buffers=None, deleting=False):
         """Close the frontend-side version of this comm"""
+        from comm import get_comm_manager
         if self._closed:
             # only close once
             return