Cirrus is dropping support for x86_64 OSX #1904
Description
Recent Cirrus CI builds display this warning: We are sunsetting support for Intel-based macOS instances! Please migrate before January 1st 2023. It looks like they do support aarch64 OSX, though. I think we'll have to demote x86_64-apple-darwin to Tier 2. Conversely, we can promote aarch64-apple-darwin to "Tier 1", though it won't really be tier 1 unless we have a maintainer who is committed to fixing any bugs on that platform.