Bump ember-test-selectors from 6.0.0 to 7.0.0 #1916

Job	Run time
Lint files	20s
Test addon (locked dependencies) (ember)	45s
Test compatibility (ember-lts-4.4)	1m 6s
Test addon (floating dependencies) (ember)	1m 5s
Test addon (locked dependencies) (node)	30s
Test compatibility (ember-lts-4.8)	1m 14s
Test addon (floating dependencies) (node)	28s
Test addon (locked dependencies) (test-apps)	55s
Test compatibility (ember-lts-4.12)	1m 6s
Test addon (floating dependencies) (test-apps)	46s
Test compatibility (ember-lts-5.4)	57s
Test compatibility (ember-release)	56s
Test compatibility (ember-beta)	57s
Test compatibility (ember-canary)	56s
Test compatibility (embroider-safe)	1m 0s
Deploy app	0s
	13m 1s

Provide feedback