Fix future `trivial_casts` lint. #341

Job	Run time
miri	1m 51s
no_std	32s
build (ubuntu, stable, locked, true)	12m 27s
build (windows, stable, locked, false)	23m 23s
build (macos, stable, locked, false)	19m 55s
build (ubuntu, nightly, locked, false)	19m 57s
build (ubuntu, beta, locked, false)	20m 1s
build (ubuntu, stable, latest, false)	17m 2s
build (ubuntu, stable, minimal, false)	15m 46s
deploy	8s
fuzz	15m 9s
features	26m 19s
	2h 52m 30s

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