Update dependency ember-cli to v6 (#294) #1472

Job	Run time
Tests	59s
Floating Dependencies	53s
ember-lts-4.12	44s
ember-lts-4.4	51s
ember-lts-5.12	43s
ember-beta	45s
ember-release	45s
no-deprecations	47s
ember-lts-4.8	1m 14s
ember-canary	45s
ember-lts-3.28	47s
ember-release-no-deprecations	44s
embroider-optimized	1m 2s
ember-modifier-3.2.7	45s
embroider-safe	56s
	12m 40s

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