CMake

Fix legacy key value format in Dockerfiles #203

Job	Run time
build (macOS 15, macos-15)	1m 12s
build (Ubuntu 22.04, ubuntu-22.04)	1m 16s
build (Ubuntu 24.04, ubuntu-24.04)	1m 30s
build (macOS 14, macos-14)	56s
build (Windows, windows-latest)	52s
integration-test (Timewarrior [stable], timew-libshared-stable)	1m 50s
integration-test (Timewarrior [develop], timew-libshared-develop)	1m 48s
integration-test (Taskwarrior [stable], task-libshared-stable)	6m 42s
integration-test (Taskwarrior [develop], task-libshared-develop)	6m 51s
	22m 57s

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