Update dependency ember-template-lint to v6 #639

Job	Run time
Floating Dependencies	50s
Tests	51s
ember-lts-3.28	55s
ember-lts-4.4	48s
ember-lts-4.8	47s
ember-lts-4.12	1m 13s
ember-lts-5.4	45s
ember-release	1m 1s
ember-beta	45s
ember-canary	53s
no-deprecations	49s
ember-release-no-deprecations	51s
embroider-safe	48s
embroider-optimized	1m 8s
ember-modifier-3.2.7	50s
	13m 14s

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