Update curve25519-dalek requirement from =4.0.0-rc.3 to =4.0.0 (#450)

Updates the requirements on [curve25519-dalek](https://github.com/dalek-cryptography/curve25519-dalek) to permit the latest version.
- [Release notes](https://github.com/dalek-cryptography/curve25519-dalek/releases)
- [Commits](dalek-cryptography/curve25519-dalek@4.0.0-rc.3...curve25519-4.0.0)

---
updated-dependencies:
- dependency-name: curve25519-dalek
  dependency-type: direct:production
...

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

frost-ed25519/Cargo.toml

@@ -22,7 +22,7 @@ description = "A Schnorr signature scheme over Ed25519 that supports FROST."
 features = ["nightly"]
 
 [dependencies]
-curve25519-dalek = { version = "=4.0.0-rc.3", features = ["serde", "rand_core"] }
+curve25519-dalek = { version = "=4.0.0", features = ["serde", "rand_core"] }
 frost-core = { path = "../frost-core", version = "0.6.0", features = ["test-impl"] }
 rand_core = "0.6"
 sha2 = "0.10.2"

frost-ristretto255/Cargo.toml

@@ -18,7 +18,7 @@ description = "A Schnorr signature scheme over the prime-order Ristretto group t
 features = ["nightly"]
 
 [dependencies]
-curve25519-dalek = { version = "=4.0.0-rc.3", features = ["serde", "rand_core"] }
+curve25519-dalek = { version = "=4.0.0", features = ["serde", "rand_core"] }
 frost-core = { path = "../frost-core", version = "0.6.0", features = ["test-impl"] }
 rand_core = "0.6"
 sha2 = "0.10.2"