pcx: Switch test images out #1682

Job	Run time
Fuzz targets (cargo-fuzz)	51s
build_benchmarks	48s
Fuzz targets (afl)	2m 8s
cargo-deny	21s
cargo-semver-checks	29s
clippy	2m 7s
public_private_dependencies	26s
rustfmt	14s
test_avif_decoding	1m 27s
test_other_archs (powerpc-unknown-linux-gnu)	2m 37s
test_features	28s
test_other_archs (i686-unknown-linux-gnu)	1m 42s
test_toolchains (1.70.0)	27s
test_features (default)	1m 48s
test_toolchains (nightly)	1m 18s
test_features (rayon)	37s
test_toolchains (beta)	1m 31s
test_features (avif)	58s
test_features (bmp)	37s
test_features (dds)	32s
test_features (exr)	46s
test_features (ff)	29s
test_features (gif)	42s
test_features (hdr)	34s
test_features (ico)	40s
test_features (jpeg)	28s
test_features (pcx)	27s
test_features (png)	34s
test_features (pnm)	29s
test_features (qoi)	37s
test_features (tga)	32s
test_features (tiff)	40s
test_features (webp)	30s
	28m 54s

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