Temporarily disable PCX format #1704

Job	Run time
Fuzz targets (afl)	2m 25s
cargo-deny	21s
Fuzz targets (cargo-fuzz)	46s
build_benchmarks	47s
cargo-semver-checks	27s
clippy	1m 58s
public_private_dependencies	26s
rustfmt	14s
test_avif_decoding	1m 25s
test_features	29s
test_other_archs (powerpc-unknown-linux-gnu)	2m 28s
test_toolchains (1.70.0)	26s
test_features (default)	1m 51s
test_other_archs (i686-unknown-linux-gnu)	1m 21s
test_features (rayon)	27s
test_toolchains (nightly)	1m 11s
test_features (avif)	1m 6s
test_toolchains (beta)	1m 18s
test_features (bmp)	32s
test_features (dds)	32s
test_features (exr)	49s
test_features (ff)	29s
test_features (gif)	26s
test_features (hdr)	28s
test_features (ico)	38s
test_features (jpeg)	30s
test_features (png)	34s
test_features (pnm)	25s
test_features (qoi)	22s
test_features (tga)	25s
test_features (tiff)	31s
test_features (webp)	36s
	26m 43s

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