Revert "Setup cross toolchain for miri" #182

Job	Run time
Miri (x86_64-unknown-linux-gnu, --no-default-features)	1m 7s
Miri (x86_64-unknown-linux-gnu)	1m 7s
Miri (x86_64-unknown-linux-gnu, --all-features)	1m 7s
Miri (aarch64-unknown-linux-gnu, --no-default-features)	1m 10s
Miri (aarch64-unknown-linux-gnu)	1m 7s
fmt	20s
feature checks	31s
Fuzz	34s
Clippy	21s
Test (x86_64-unknown-linux-gnu, nightly)	25s
Test (x86_64-unknown-linux-gnu, beta)	22s
Test (x86_64-unknown-linux-gnu, stable)	26s
Test (x86_64-unknown-linux-gnu, 1.64)	26s
Test (aarch64-unknown-linux-gnu, nightly)	53s
Test (aarch64-unknown-linux-gnu, beta)	44s
Test (aarch64-unknown-linux-gnu, stable)	1m 27s
Test (aarch64-unknown-linux-gnu, 1.64)	1m 4s
docs	22s
Outdated	7s
	13m 40s

Provide feedback