Update quickcheck requirement from 0.7 to 0.8

Updates the requirements on [quickcheck](https://github.com/BurntSushi/quickcheck) to permit the latest version.
- [Release notes](https://github.com/BurntSushi/quickcheck/releases)
- [Commits](https://github.com/BurntSushi/quickcheck/commits/quickcheck_macros-0.8.0)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot-support

crates/stdsimd/Cargo.toml

@@ -29,7 +29,7 @@ cfg-if = "0.1"
 
 [dev-dependencies]
 auxv = "0.3.3"
-quickcheck = "0.7"
+quickcheck = "0.8"
 rand = "0.6"
 cupid = "0.6.0"