Describe the bug:

The validating webhook has an incorrect error message if the key type is not valid. It doesn't mention Ed25519.

There should also be tests for ed25519 in the corresponding test file: https://github.com/cert-manager/cert-manager/blob/d2f6bbe579fd9d5f88b82f9a4bfe9241709e9eb8/internal/apis/certmanager/validation/certificate_test.go

/kind bug