macOS CI runner changed from x86_64 to Arm64

[edvinolo]

In the supported compilers table in README.md, the architecture for macOS 14 is listed as x86_64. However, the macos-14 CI runner that was added in #1042 is Arm64-based. Should the table be updated to reflect this, and is there a preferred label for this architecture, Arm64 or AArch64? If an x86_64-based runner is still wanted, then macos-15-intel could be used instead of the soon-to-be-removed macos-13.

[jvdp1]

Thank you for the heads up, @edvinolo . The table should be updated. I suggest to use Arm64. Would you like to open a PR to update the table?