Fix: macOS CI deprecation

[dragonmux]

Detailed description

In this PR we address the upcoming macOS 12 GHA deprecation and switch-off scheduled for the 3rd of December this year. This moves CI entirely to macOS 13 and 14 (latest), with 15 currently in beta.

Your checklist for this pull request

• [x] I've read the Code of Conduct
• [x] I've read the guidelines for contributing to this repository
• [x] It builds for hardware native (see Building the firmware)
• [x] It builds as BMDA (see Building the BMDA)
• [x] I've tested it to the best of my ability
• [x] My commit messages provide a useful short description of what the commits do

Closing issues