Use ED25519 scheme to sign metadata in the test uptane repo
Use ED25519 scheme to sign metadata in the test uptane repo

Signed-off-by: Mykhaylo Sul <70fbe5867b3824dc0357f3c0d748126b454c39d4@gmail.com>

advancedtelematic/aktualizr,advancedtelematic/sota_client_cpp,advancedtelematic/aktualizr,advancedtelematic/aktualizr,advancedtelematic/aktualizr,advancedtelematic/sota_client_cpp