use newly introduced stdarch features for avx512 to compiler on nightly

see

rust-lang/rust#117372

Author: IceTDrinker

pulp/src/lib.rs

@@ -62,7 +62,7 @@
     clippy::too_many_arguments,
     clippy::type_complexity
 )]
-#![cfg_attr(feature = "nightly", feature(stdsimd), feature(avx512_target_feature))]
+#![cfg_attr(feature = "nightly", feature(stdarch_x86_avx512), feature(avx512_target_feature))]
 #![cfg_attr(not(feature = "std"), no_std)]
 #![cfg_attr(docsrs, feature(doc_cfg))]