Update ark-std requirement from 0.5.0 to 0.6.0

Updates the requirements on [ark-std](https://github.com/arkworks-rs/std) to permit the latest version.
- [Changelog](https://github.com/arkworks-rs/std/blob/master/CHANGELOG.md)
- [Commits](arkworks-rs/std@v0.5.0...v0.6.0)

---
updated-dependencies:
- dependency-name: ark-std
  dependency-version: 0.6.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

Cargo.toml

@@ -25,7 +25,7 @@ ark-ff = { git = "https://github.com/arkworks-rs/algebra.git", default-features
 ark-ec = { git = "https://github.com/arkworks-rs/algebra.git", default-features = false }
 ark-serialize = { git = "https://github.com/arkworks-rs/algebra.git", default-features = false, features = [ "derive" ] }
 ark-poly = { git = "https://github.com/arkworks-rs/algebra.git", default-features = false }
-ark-std = { version = "0.5.0", default-features = false }
+ark-std = { version = "0.6.0", default-features = false }
 
 ark-relations = { git = "https://github.com/arkworks-rs/snark.git", default-features = false }
 ark-snark = { git = "https://github.com/arkworks-rs/snark.git", default-features = false }