TYP: Create DeepChainMap from ChainMap.new_child in scope.py
xref #37715

scope is created as a DeepChainMap but on lines 139, 145, 262 call to new_child was returning ChainMap. Created a new DeepChainMap from the resulting ChainMap.
Hello @kashifkhan! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:



There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2021-12-11 15:17:11 UTC @kashifkhan seems to be failing precommit; you can run this locally (and fix up) CI should be fixed if you merge master > CI should be fixed if you merge master

Sure Ill take care of this tomorrow !! thanks @kashifkhan 