Add CI tests for macOS Tahoe (26.x)

[geerlingguy]

It will be a simple one-line addition, but hopefully now that I've been working through #232, this playbook should be compatible with Tahoe as well. See GitHub Actions' list of images:

https://github.com/actions/runner-images?tab=readme-ov-file#available-images

Right now the 26 image is in beta, but once it's not, we could add it to the CI list.

[rafael-c-alexandre]

@geerlingguy not exclusive to Tahoe but I see the CI doesn't check the mas integration, which would be very difficult to do with GitHub Actions (if not impossible). As reported in this issue, the mas list command errors out when the list is empty. This will fail the playbook so maybe good to also address it either with the proposed solution or some other.