Update curve25519-dalek requirement from 3 to 4

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@3.0.0...3.2.1)

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

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

curve25519-parser/Cargo.toml

@@ -14,7 +14,7 @@ readme = "../README.md"
 [dependencies]
 der-parser = { version = "8", default-features = false}
 x25519-dalek = { version = "1", default-features = false}
-curve25519-dalek = { version = "3", default-features = false, features = ["u64_backend"]}
+curve25519-dalek = { version = "4", default-features = false, features = ["u64_backend"]}
 sha2 = { version = "0", default-features = false}
 pem = { version = "2", default-features = false}