CI/Linux: Build/publish Docker images used to create AppImages #269

Job	Run time
Code Linting / Format / Lint	8s
Linux / deb (release, Qt 5, ubuntu-20_04)	1m 22s
Linux / snap	4m 26s
Linux / deb (release, Qt 6, ubuntu-22_04)	2m 10s
Linux / rpm (release, Qt 6, fedora)	2m 4s
Linux / deb (release, Qt 6, ubuntu-23_10)	2m 13s
Linux / rpm (release, Qt 6, opensuse)	2m 33s
macOS / Build (debug, homebrew (qt5), macos-12)	2m 10s
macOS / dmg (release, Qt 5.15.2, macos-12)	3m 56s
macOS / dmg (release, Qt 6.5.2, macos-12)	4m 28s
macOS / Build (debug, homebrew (qt6), macos-12)	2m 49s
Windows / Build (x64, release, Qt 5.15.2, windows-2019)	2m 19s
Linux / AppImage (release, Qt 5, appimage-qt5)	2m 50s
Windows / Build (x86, release, Qt 5.15.2, windows-2019)	1m 48s
Linux / AppImage (release, Qt 6, appimage-qt6)	2m 54s
Windows / Build (x64, release, Qt 6.4.3, windows-2019)	2m 30s
Windows / Unified x64-x86 Installer	55s
	41m 35s

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