Update ed25519-zebra requirement from 3.0.0 to 4.0.0 (#393)

Updates the requirements on [ed25519-zebra](https://github.com/ZcashFoundation/ed25519-zebra) to permit the latest version.
- [Release notes](https://github.com/ZcashFoundation/ed25519-zebra/releases)
- [Changelog](https://github.com/ZcashFoundation/ed25519-zebra/blob/main/CHANGELOG.md)
- [Commits](https://github.com/ZcashFoundation/ed25519-zebra/compare/3.0.0...4.0.0)

---
updated-dependencies:
- dependency-name: ed25519-zebra
  dependency-type: direct:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

frost-ed25519/Cargo.toml

@@ -31,7 +31,7 @@ sha2 = "0.10.2"
 bincode = "1"
 criterion = "0.5"
 ed25519-dalek = "1.0.1"
-ed25519-zebra = "3.0.0"
+ed25519-zebra = "4.0.0"
 hex = "0.4.3"
 lazy_static = "1.4"
 proptest = "1.0"

frost-p256/Cargo.toml

@@ -31,7 +31,7 @@ sha2 = "0.10.2"
 bincode = "1"
 criterion = "0.5"
 ed25519-dalek = "1.0.1"
-ed25519-zebra = "3.0.0"
+ed25519-zebra = "4.0.0"
 hex = "0.4.3"
 lazy_static = "1.4"
 proptest = "1.0"

frost-ristretto255/Cargo.toml

@@ -27,7 +27,7 @@ sha2 = "0.10.2"
 bincode = "1"
 criterion = { version = "0.5", features = ["html_reports"] }
 ed25519-dalek = "1.0.1"
-ed25519-zebra = "3.0.0"
+ed25519-zebra = "4.0.0"
 lazy_static = "1.4"
 proptest = "1.0"
 proptest-derive = "0.3"

frost-secp256k1/Cargo.toml

@@ -30,7 +30,7 @@ sha2 = "0.10.2"
 bincode = "1"
 criterion = "0.5"
 ed25519-dalek = "1.0.1"
-ed25519-zebra = "3.0.0"
+ed25519-zebra = "4.0.0"
 hex = "0.4.3"
 lazy_static = "1.4"
 proptest = "1.0"