Add support for CMS 6 #25

Job	Run time
CI / Context	4s
CI / Generate matrix	13s
CI / 8.3 mysql80 phpunit all	2m 15s
CI / 8.3 mysql80 phplinting	1m 46s
CI / 8.3 mysql80 endtoend root	3m 25s
CI / Check governance	0s
CI / Dispatch tag patch release	0s
	7m 43s

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