Set CONAN_HOME in every image with Conan installed (#12) #95

Job	Run time
build (linux/amd64, ubuntu-24.04, bookworm, clang, 18)	1m 32s
build (linux/amd64, ubuntu-24.04, bookworm, clang, 17)	1m 32s
build (linux/amd64, ubuntu-24.04, bookworm, gcc, 12)	1m 30s
build (linux/amd64, ubuntu-24.04, bookworm, clang, 16)	1m 31s
build (linux/amd64, ubuntu-24.04, bookworm, clang, 19)	1m 29s
build (linux/amd64, ubuntu-24.04, bookworm, gcc, 14)	1m 29s
build (linux/arm64, ubuntu-24.04-arm, bookworm, gcc, 12)	2m 27s
build (linux/amd64, ubuntu-24.04, bookworm, gcc, 13)	1m 42s
build (linux/arm64, ubuntu-24.04-arm, bookworm, gcc, 13)	2m 17s
build (linux/arm64, ubuntu-24.04-arm, bookworm, gcc, 14)	2m 3s
build (linux/amd64, ubuntu-24.04, bookworm, clang, 20)	1m 33s
build (linux/arm64, ubuntu-24.04-arm, bookworm, clang, 18)	2m 11s
build (linux/arm64, ubuntu-24.04-arm, bookworm, clang, 16)	1m 54s
build (linux/arm64, ubuntu-24.04-arm, bookworm, clang, 17)	2m 15s
build (linux/arm64, ubuntu-24.04-arm, bookworm, clang, 19)	1m 53s
build (linux/arm64, ubuntu-24.04-arm, bookworm, clang, 20)	1m 58s
merge (bookworm, clang, 17)	17s
merge (bookworm, gcc, 12)	19s
merge (bookworm, clang, 20)	14s
merge (bookworm, clang, 16)	13s
merge (bookworm, gcc, 13)	14s
merge (bookworm, clang, 19)	18s
merge (bookworm, clang, 18)	21s
merge (bookworm, gcc, 14)	16s
	31m 28s

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