[consutil] Fix issue where the ConfigDBConnector's reference is missing (sonic-net#1117)

Co-authored-by: Jing Kan<[email protected]>

Author: Blueve

consutil/lib.py

@@ -10,6 +10,7 @@
     import re
     import subprocess
     import sys
+    from swsssdk import ConfigDBConnector
 except ImportError as e:
     raise ImportError("%s - required module not found" % str(e))