Fix `rustfmt` for latest nightly Rust #742

Job	Run time
clippy	34s
MSRV (1.70.0, cucumber-codegen, ubuntu)	1m 18s
feature (<none>)	34s
MSRV (1.70.0, cucumber-codegen, macOS)	2m 1s
rustdoc (cucumber-codegen)	24s
feature (macros)	44s
rustdoc (cucumber)	56s
MSRV (1.70.0, cucumber-codegen, windows)	2m 18s
feature (timestamps)	39s
MSRV (1.70.0, cucumber, ubuntu)	3m 27s
rustfmt	11s
feature (output-json)	41s
MSRV (1.70.0, cucumber, macOS)	5m 16s
feature (output-junit)	33s
feature (libtest)	40s
MSRV (1.70.0, cucumber, windows)	4m 19s
feature (tracing)	35s
test (cucumber-codegen, stable, ubuntu)	55s
test (Book, ubuntu)	5m 58s
test (cucumber-codegen, stable, macOS)	2m 41s
test (Book, macOS)	7m 27s
test (cucumber-codegen, stable, windows)	3m 23s
test (Book, windows)	8m 14s
test (cucumber-codegen, beta, ubuntu)	1m 2s
test (cucumber-codegen, beta, macOS)	2m 41s
test (cucumber-codegen, beta, windows)	2m 21s
test (cucumber-codegen, nightly, ubuntu)	1m 39s
test (cucumber-codegen, nightly, macOS)	4m 7s
test (cucumber-codegen, nightly, windows)	2m 51s
test (cucumber, stable, ubuntu)	3m 7s
test (cucumber, stable, macOS)	5m 34s
test (cucumber, stable, windows)	5m 7s
test (cucumber, beta, ubuntu)	3m 4s
test (cucumber, beta, macOS)	4m 23s
test (cucumber, beta, windows)	4m 33s
test (cucumber, nightly, ubuntu)	3m 49s
test (cucumber, nightly, macOS)	7m 1s
test (cucumber, nightly, windows)	5m 43s
deploy (Book)	9s
release (GitHub)	0s
pr	0s
publish (crates.io)	0s
	1h 50m 59s

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