Use void in parameterless functions #1705

Job	Run time
docs	27s
minimal	21s
check-cfg	29s
msrv	3m 56s
quickchecking	20s
rustfmt-clippy	40s
test-book	14s
test (ubuntu-latest, 5.0, 1, 0, 0, 0, 0)	3m 0s
test (ubuntu-latest, 5.0, 1, 0, 0, 1, 0)	2m 58s
test (ubuntu-latest, 5.0, 1, 0, 1, 0, 0)	4m 42s
test (ubuntu-latest, 5.0, 1, 0, 1, 1, 0)	2m 46s
test (ubuntu-latest, 5.0, 1, 1, 0, 0, 0)	3m 21s
test (ubuntu-latest, 5.0, 1, 1, 0, 1, 0)	3m 14s
test (ubuntu-latest, 5.0, 1, 1, 1, 0, 0)	3m 26s
test (ubuntu-latest, 5.0, 1, 1, 1, 1, 0)	3m 26s
test (ubuntu-latest, 9.0, 1, 0, 0, 0, 0)	3m 43s
test (ubuntu-latest, 9.0, 1, 0, 0, 1, 0)	3m 25s
test (ubuntu-latest, 9.0, 1, 0, 1, 0, 0)	3m 27s
test (ubuntu-latest, 9.0, 1, 0, 1, 1, 0)	3m 38s
test (ubuntu-latest, 9.0, 1, 1, 0, 0, 0)	4m 44s
test (ubuntu-latest, 9.0, 1, 1, 0, 1, 0)	3m 52s
test (ubuntu-latest, 9.0, 1, 1, 1, 0, 0)	4m 11s
test (ubuntu-latest, 9.0, 1, 1, 1, 1, 0)	3m 52s
test (ubuntu-latest, 9.0, 0, 0, 1)	2m 34s
test (macos-latest, 9.0, 0, 0, 0)	2m 3s
test-expectations (ubuntu-latest)	2m 12s
test-expectations (macos-latest)	4m 3s
	1h 15m 4s

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