Fix clippy lint in test suite #1481

Job	Run time
test_features	15s
Fuzz targets (cargo-fuzz)	51s
build_benchmarks	47s
Fuzz targets (afl)	2m 7s
test_features (default)	1m 53s
clippy	2m 2s
public_private_dependencies	25s
test_features (rayon)	25s
rustfmt	4s
test_features (avif)	1m 1s
test_avif_decoding	1m 43s
test_features (bmp)	18s
test_other_archs (powerpc-unknown-linux-gnu)	2m 13s
test_toolchains (1.67.1)	32s
test_features (dds)	21s
test_other_archs (i686-unknown-linux-gnu)	1m 13s
test_toolchains (nightly)	1m 8s
test_features (exr)	38s
cargo-deny	22s
test_toolchains (beta)	1m 17s
test_features (ff)	21s
test_features (gif)	18s
cargo-semver-checks	26s
test_features (hdr)	17s
test_features (ico)	26s
test_features (jpeg)	34s
test_features (png)	25s
test_features (pnm)	33s
test_features (qoi)	30s
test_features (tga)	33s
test_features (tiff)	23s
test_features (webp)	24s
	24m 45s

Provide feedback