Pass through rayon feature to ravif #1631

Job	Run time
test_avif_decoding	1m 19s
test_features	24s
test_features (default)	1m 47s
test_features (rayon)	25s
build_benchmarks	48s
test_features (avif)	58s
Fuzz targets (afl)	2m 4s
Fuzz targets (cargo-fuzz)	49s
test_features (bmp)	29s
test_features (dds)	24s
clippy	2m 7s
test_features (exr)	37s
public_private_dependencies	23s
rustfmt	10s
test_features (ff)	25s
test_features (gif)	24s
test_other_archs (powerpc-unknown-linux-gnu)	2m 30s
test_features (hdr)	19s
test_other_archs (i686-unknown-linux-gnu)	1m 28s
test_features (ico)	29s
test_toolchains (1.70.0)	26s
test_toolchains (nightly)	1m 22s
test_features (jpeg)	20s
cargo-deny	20s
test_features (png)	28s
test_toolchains (beta)	1m 33s
test_features (pnm)	24s
test_features (qoi)	16s
cargo-semver-checks	25s
test_features (tga)	17s
test_features (tiff)	30s
test_features (webp)	40s
	25m 20s

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