The dockerfile we were using in the cfn-python-lint repo wasn't actually pinned to the version associated with the git tag, it always installs the latest version.
A recent release consolidated error rules regarding invalid values.
We use an invalid "us-test-1" region and zones in much of our testing.
We used to be able to ignore this "invalid AZ" error, but now we would need to ignore all invalid values for all resource properties.
This pins cfn-python-lint to an older version but we'll have to figure out how we want to handle this longer term.