Clippy lints #642

Job	Run time
Miri	2m 34s
benchmarks	1m 55s
documentation	1m 29s
clippy	1m 8s
Optional features (approx selected)	33s
Optional features (none selected)	31s
rustfmt	19s
static SuiteSparse (stable, ubuntu-20.04, stable)	35s
static SuiteSparse (macos, macos-latest, stable)	51s
test (msrv, ubuntu-20.04, 1.77.0)	1m 5s
static SuiteSparse (win-msvc, windows-2019, stable)	1m 35s
static SuiteSparse (win-gnu, windows-2019, stable)	1m 11s
test (stable, ubuntu-20.04, stable)	1m 2s
test (beta, ubuntu-20.04, beta)	1m 3s
test (nightly, ubuntu-20.04, nightly)	57s
test (macos, macos-latest, stable)	1m 5s
test (win-msvc, windows-2019, stable)	2m 15s
test (win-gnu, windows-2019, stable)	2m 14s
	22m 22s

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