Ember-Table CI

Bump qunit from 2.20.0 to 2.20.1 #623

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Run time

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Job	Run time
Run Tests	2m 11s
Run Tests (ember-lts-3.12)	4m 47s
Run Tests (ember-lts-3.20)	2m 43s
Run Tests (ember-lts-3.24)	2m 41s
Run Tests (ember-lts-3.28)	2m 41s
Run Tests (ember-lts-4.4)	3m 9s
Run Tests (ember-lts-4.12)	2m 38s
Run Tests (ember-default-docs)	2m 37s
	23m 27s