Sync auto-assign-pr.yml from .github repo #17

Job	Run time
test-review-and-execution (chromium, headed)	39s
test-review-and-execution (webkit, headed)	58s
test-review-and-execution (webkit, headless)	1m 8s
test-review-and-execution (firefox, headless)	51s
test-review-and-execution (chromium, headless)	44s
test-review-and-execution (firefox, headed)	50s
test-coverage-review	3s
	5m 13s

Provide feedback