CI/macOS: Update to macOS 12 #232

Job	Run time
Code Linting / Format / Lint	8s
macOS / Build (debug, homebrew (qt5), macos-12)	1m 46s
Windows / Build (x64, release, Qt 5.15.2, windows-2019)	2m 28s
macOS / dmg (release, Qt 5.15.2, macos-12)	4m 54s
Windows / Build (x86, release, Qt 5.15.2, windows-2019)	2m 27s
macOS / dmg (release, Qt 6.5.2, macos-12)	6m 45s
Windows / Build (x64, release, Qt 6.4.3, windows-2019)	3m 6s
Linux / AppImage (release, Qt 5.15.2, ubuntu-aqtinstall-5)	1m 45s
macOS / Build (debug, homebrew (qt6), macos-12)	2m 23s
Linux / AppImage (release, Qt 6.4.3, ubuntu-aqtinstall-6)	3m 3s
Linux / deb (release, Qt 5, ubuntu-20_04)	1m 34s
Linux / snap	6m 4s
Linux / rpm (release, Qt 6, fedora)	1m 58s
Linux / deb (release, Qt 6, ubuntu-22_04)	2m 16s
Linux / rpm (release, Qt 6, opensuse)	2m 47s
Linux / deb (release, Qt 6, ubuntu-23_10)	2m 27s
Windows / Unified x64-x86 Installer	47s
	46m 38s

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