Build on macOS 13 in CI

[fwcd]

Given that GitHub has phased out macOS 11 runners, we have to migrate to a newer macOS version.

[fwcd]

Looks like Xcode 14.3 broke the build by no longer accepting std::result_of, which also was formally removed in C++20:

In file included from <my mixxx root>/lib/reverb/Reverb.cc:46:
In file included from <my mixxx root>/lib/reverb/basics.h:46:
In file included from <my mixxx root>/src/util/types.h:6:
In file included from <my mixxx root>/src/util/math.h:7:
In file included from <my mixxx root>/src/util/assert.h:3:
In file included from <my vcpkg root>/installed/arm64-osx/include/qt5/QtCore/QtDebug:1:
In file included from <my vcpkg root>/installed/arm64-osx/include/qt5/QtCore/qdebug.h:49:
In file included from <my vcpkg root>/installed/arm64-osx/include/qt5/QtCore/qtextstream.h:43:
In file included from <my vcpkg root>/installed/arm64-osx/include/qt5/QtCore/qiodevice.h:45:
In file included from <my vcpkg root>/installed/arm64-osx/include/qt5/QtCore/qobject.h:46:
<my vcpkg root>/installed/arm64-osx/include/qt5/QtCore/qobjectdefs.h:535:65: error: no type named 'result_of' in namespace 'std'
    invokeMethod(QObject *context, Func function, typename std::result_of<Func()>::type *ret)
                                                  ~~~~~~~~~~~~~~^~~~~~~~~
<my vcpkg root>/installed/arm64-osx/include/qt5/QtCore/qobjectdefs.h:535:74: error: expected ')'
    invokeMethod(QObject *context, Func function, typename std::result_of<Func()>::type *ret)
                                                                         ^
<my vcpkg root>/installed/arm64-osx/include/qt5/QtCore/qobjectdefs.h:535:17: note: to match this '('
    invokeMethod(QObject *context, Func function, typename std::result_of<Func()>::type *ret)
                ^
<my vcpkg root>/installed/arm64-osx/include/qt5/QtCore/qobjectdefs.h:540:33: error: use of undeclared identifier 'ret'
                                ret);
                                ^
3 errors generated.
ninja: build stopped: subcommand failed.

Qt 5.14.2 seems to be the first version that patches this (see qt/qtbase@fb6acf0). The upstream vcpkg branch patches this in mixxxdj/vcpkg#70.

Eventually, Mixxx plans to move towards Qt 6 in 2.5, there seem to be some crosscompiling issues, however (see mixxxdj/vcpkg#73) and the CI builds of #33.

[fwcd]

Unfortunately, CI still seems to sporadically fail, likely due to a race condition somewhere between cpack and hdiutil: https://gitlab.kitware.com/cmake/cmake/-/issues/25671