Merge pull request #571 from apiraino/rustfmt-2018-edition-default #306

Job	Run time
test (macos-latest, 28.2)	2m 54s
test (ubuntu-latest, 26.3)	39s
test (ubuntu-latest, 27.2)	51s
test (ubuntu-latest, 28.2)	45s
test (ubuntu-latest, 29.4)	6m 9s
test (ubuntu-latest, 30.1)	9m 14s
test (macos-latest, 29.4)	5m 19s
test (macos-latest, 30.1)	7m 55s
test (windows-latest, 26.3)	16m 41s
test (windows-latest, 27.2)	10m 39s
test (windows-latest, 29.4)	15m 9s
test (ubuntu-latest, snapshot, true)	48s
test (windows-latest, 28.2)	14m 2s
test (macos-latest, snapshot, true)	2m 58s
test (windows-latest, snapshot, true)	16m 36s
test (windows-latest, 30.1)	9m 7s
	1h 59m 46s

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