build: bump curve25519-dalek

Bumps the cargo group with 1 update in the
/packages/cacti-plugin-ledger-connector-stellar/src/test/rust/demo-contract
directory: [curve25519-dalek](https://github.com/dalek-cryptography/curve25519-dalek).

Updates `curve25519-dalek` from 4.1.1 to 4.1.2
- [Release notes](https://github.com/dalek-cryptography/curve25519-dalek/releases)
- Commits:
dalek-cryptography/curve25519-dalek@curve25519-4.1.1...curve25519-4.1.2

---
updated-dependencies:
- dependency-name: curve25519-dalek
  dependency-type: indirect
  dependency-group: cargo
...

Co-authored-by: Peter Somogyvari <[email protected]>

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