Google Maps is pretty robust that you don't need to regularly regression test the integration. I would think you don't actually have every test case automated at your organization? The Google Maps integration I think is better tested manually once in a while to ensure still works rather than trying to automate the coverage.
If you do want to automate, suggest you consider partial automation coverage as sanity check some basic functionality but not try to cover all the functionality of Google Maps that you've integrated/embedded to your site. Because full coverage without flaky test result would be hard to strive for, for something dynamic like that along with it being a 3rd party dependency.