Revert "Temporarily disable PCX format" #1706

Job	Run time
build_benchmarks	44s
Fuzz targets (cargo-fuzz)	1m 6s
Fuzz targets (afl)	2m 11s
cargo-deny	17s
cargo-semver-checks	33s
clippy	2m 2s
public_private_dependencies	24s
rustfmt	11s
test_avif_decoding	1m 28s
test_features	23s
test_other_archs (powerpc-unknown-linux-gnu)	2m 51s
test_features (default)	1m 46s
test_toolchains (1.70.0)	27s
test_other_archs (i686-unknown-linux-gnu)	1m 27s
test_features (rayon)	34s
test_toolchains (nightly)	1m 13s
test_features (avif)	1m 8s
test_toolchains (beta)	1m 28s
test_features (bmp)	31s
test_features (dds)	28s
test_features (exr)	39s
test_features (ff)	27s
test_features (gif)	30s
test_features (hdr)	25s
test_features (ico)	35s
test_features (jpeg)	26s
test_features (pcx)	25s
test_features (png)	31s
test_features (pnm)	25s
test_features (qoi)	24s
test_features (tga)	28s
test_features (tiff)	32s
test_features (webp)	35s
	27m 34s

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