Temporarily disable PCX format (#2379) #1705

Job	Run time
cargo-deny	17s
Fuzz targets (cargo-fuzz)	51s
build_benchmarks	46s
Fuzz targets (afl)	2m 5s
clippy	2m 28s
cargo-semver-checks	29s
public_private_dependencies	23s
rustfmt	14s
test_avif_decoding	1m 20s
test_features	29s
test_features (default)	1m 50s
test_toolchains (1.70.0)	35s
test_other_archs (powerpc-unknown-linux-gnu)	3m 4s
test_features (rayon)	28s
test_toolchains (nightly)	1m 50s
test_other_archs (i686-unknown-linux-gnu)	1m 45s
test_features (avif)	1m 6s
test_toolchains (beta)	1m 41s
test_features (bmp)	31s
test_features (dds)	32s
test_features (exr)	42s
test_features (ff)	24s
test_features (gif)	27s
test_features (hdr)	26s
test_features (ico)	34s
test_features (jpeg)	27s
test_features (png)	37s
test_features (pnm)	28s
test_features (qoi)	28s
test_features (tga)	24s
test_features (tiff)	31s
test_features (webp)	29s
	28m 41s

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