ci: use macos-14

[v1v]

the macOS 12 runner image will be removed by December 3rd, 2024

I guess we can use latest as we normally are using the latest OS version

Version 14.0 is not available anymore.

Switching Xcode to version '14.0'...
Available versions:
┌─────────┬──────────┬─────────────┬─────────────┬────────┬───────────────────────────────────────┐
│ (index) │ version │ buildNumber │ releaseType │ stable │ path │
├─────────┼──────────┼─────────────┼─────────────┼────────┼───────────────────────────────────────┤
│ 0 │ '16.1.0' │ '16B5014f' │ 'Beta' │ false │ '/Applications/Xcode_16.1_beta_2.app' │
│ 1 │ '16.0.0' │ '16A242d' │ 'GM' │ true │ '/Applications/Xcode_16.app' │
│ 2 │ '15.4.0' │ '15F31d' │ 'GM' │ true │ '/Applications/Xcode_15.4.app' │
│ 3 │ '15.3.0' │ '15E204a' │ 'GM' │ true │ '/Applications/Xcode_15.3.app' │
│ 4 │ '15.2.0' │ '15C500b' │ 'GM' │ true │ '/Applications/Xcode_15.2.app' │
│ 5 │ '15.1.0' │ '15C65' │ 'GM' │ true │ '/Applications/Xcode_15.1.app' │
│ 6 │ '15.0.1' │ '15A507' │ 'GM' │ true │ '/Applications/Xcode_15.0.1.app' │
│ 7 │ '14.3.1' │ '14E300c' │ 'GM' │ true │ '/Applications/Xcode_14.3.1.app' │
└─────────┴──────────┴─────────────┴─────────────┴────────┴───────────────────────────────────────┘