Pass through rayon feature to ravif #1634

Job	Run time
test_other_archs (powerpc-unknown-linux-gnu)	2m 42s
test_other_archs (i686-unknown-linux-gnu)	1m 35s
build_benchmarks	47s
Fuzz targets (cargo-fuzz)	51s
Fuzz targets (afl)	2m 8s
clippy	2m 6s
public_private_dependencies	23s
rustfmt	6s
test_avif_decoding	1m 19s
test_features	18s
test_toolchains (1.70.0)	26s
test_features (default)	1m 47s
cargo-deny	20s
test_toolchains (nightly)	1m 13s
test_features (rayon)	36s
test_toolchains (beta)	1m 30s
test_features (avif)	1m 0s
cargo-semver-checks	26s
test_features (bmp)	23s
test_features (dds)	26s
test_features (exr)	43s
test_features (ff)	22s
test_features (gif)	22s
test_features (hdr)	18s
test_features (ico)	32s
test_features (jpeg)	22s
test_features (png)	22s
test_features (pnm)	17s
test_features (qoi)	22s
test_features (tga)	17s
test_features (tiff)	31s
test_features (webp)	43s
	25m 33s

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