CMake

Fix legacy key value format in Dockerfiles #201

Job	Run time
build (macOS 15, macos-15)	1m 0s
build (Windows, windows-latest)	58s
build (macOS 14, macos-14)	57s
build (Ubuntu 24.04, ubuntu-24.04)	1m 26s
build (Ubuntu 22.04, ubuntu-22.04)	1m 24s
integration-test (Timewarrior [stable], timew-libshared-stable)	1m 53s
integration-test (Timewarrior [develop], timew-libshared-develop)	2m 3s
integration-test (Taskwarrior [develop], task-libshared-develop)	6m 39s
integration-test (Taskwarrior [stable], task-libshared-stable)	6m 23s
	22m 43s

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