Bump ember-cli-flash from 5.0.1 to 5.1.0 #5718

Job	Run time
Build (20)	2m 55s
Build With Embroider	24s
frontend Test (20)	9m 33s
Test With Embroider	25s
test-app Test (20)	4m 12s
Lint	1m 7s
lti-course-manager Test (20)	1m 5s
lti-dashboard Test (20)	1m 6s
frontend Firefox latest-esr	9m 13s
test-app Firefox latest-esr	4m 22s
lti-course-manager Firefox latest-esr	1m 12s
lti-dashboard Firefox latest-esr	1m 14s
	36m 48s

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