Update curve25519-dalek requirement from =4.0.0-rc.1 to =4.0.0-rc.2 (#108)

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)
- [Changelog](https://github.com/dalek-cryptography/curve25519-dalek/blob/main/CHANGELOG.md)
- [Commits](https://github.com/dalek-cryptography/curve25519-dalek/compare/4.0.0-rc.1...4.0.0-rc.2)

---
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>

Cargo.toml

@@ -21,7 +21,7 @@ serde = ["generic-array/serde", "dep:serde"]
 std = ["alloc"]
 
 [dependencies]
-curve25519-dalek = { version = "=4.0.0-rc.1", default-features = false, features = [
+curve25519-dalek = { version = "=4.0.0-rc.2", default-features = false, features = [
   "rand_core",
   "zeroize",
 ], optional = true }