Remove macos 12 (was deprecated and removed) and switch to 13 #1048

Job	Run time
build-unix (ubuntu-20.04, qtBase_6.7.2_ubuntu20.zip, libde265.so, libde265-internals.so, YUView.U...	6m 37s
build-unix-native (ubuntu-20.04, libgl1-mesa-dev libxkbcommon-x11-0 libpcre2-16-0 qt5-default, qm...	4m 28s
build-mac-native (macos-13)	7m 30s
build-unix-native (ubuntu-22.04, qt6-base-dev, qmake6)	4m 39s
build-windows (windows-2019, true, YUView-Win2019.zip, qtBase_6.7.2_win2019.zip)	7m 38s
build-mac-native (macos-14)	3m 32s
build-windows (windows-2019, false, YUView-Win2019-noautoupdate.zip, qtBase_6.7.2_win2019.zip)	7m 17s
build-unix (macos-13, qtBase_6.7.2_mac13.zip, libde265.dylib, libde265-internals.dylib, YUView-Ma...	7m 58s
build-unix (macos-14, qtBase_6.7.2_mac14.zip, libde265.dylib, libde265-internals.dylib, YUView-Ma...	3m 41s
	53m 20s

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