fix very small typo #2401

Job	Run time
docs	25s
minimal	17s
check-cfg	19s
msrv	52s
quickchecking	21s
rustfmt-clippy	25s
test (ubuntu-latest, 9.0, 1, 0, 0, 0, 0)	1m 50s
test-book	11s
test (ubuntu-latest, 9.0, 1, 0, 0, 1, 0)	1m 48s
test-expectations (ubuntu-latest)	55s
test (ubuntu-latest, 9.0, 1, 0, 1, 0, 0)	1m 58s
test-expectations (macos-12)	1m 11s
test (ubuntu-latest, 9.0, 1, 0, 1, 1, 0)	1m 49s
test (ubuntu-latest, 9.0, 1, 1, 0, 0, 0)	2m 18s
test (ubuntu-latest, 9.0, 1, 1, 0, 1, 0)	2m 16s
test (ubuntu-latest, 9.0, 1, 1, 1, 0, 0)	2m 13s
test (ubuntu-latest, 9.0, 1, 1, 1, 1, 0)	2m 21s
test (ubuntu-latest, 16.0, 1, 0, 0, 0, 0)	3m 57s
test (ubuntu-latest, 16.0, 1, 0, 0, 1, 0)	4m 9s
test (ubuntu-latest, 16.0, 1, 0, 1, 0, 0)	3m 58s
test (ubuntu-latest, 16.0, 1, 0, 1, 1, 0)	3m 55s
test (ubuntu-latest, 16.0, 1, 1, 0, 0, 0)	4m 8s
test (ubuntu-latest, 16.0, 1, 1, 0, 1, 0)	4m 9s
test (ubuntu-latest, 16.0, 1, 1, 1, 0, 0)	4m 7s
test (ubuntu-latest, 16.0, 1, 1, 1, 1, 0)	4m 8s
test (ubuntu-latest, 16.0, 0, 0, 1)	1m 51s
test (macos-12, 9.0, 0, 0, 0)	2m 9s
success	1s
	58m 1s

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