Review Script to check for removal of previous deployment types

[remedcu]

The current review script only checks for line changes, not the exact change in the deployment types.

So, if say there is an entry as:

    "someChainID": ["canonical", "eip155"]

then, if the PR removes one of the deployment types, it will still pass the review check.

    "someChainID": "canonical"

This issue is limited to v1.3.1.

Expected Outcome

To check the PR is not removing any current deployment types from the deployment list.