- Add a new job `support-ed25519-key` to the GitHub Actions workflow
- Add steps to the new job for checking out code, adding public and private keys to the environment, and creating a new SSH server
- Add steps to the new job for testing the `id_ed25519` key using `appleboy/ssh-action`
- Add a new private SSH key file `testdata/.ssh/id_ed25519`
- Add a new public SSH key file `testdata/.ssh/id_ed25519.pub`
Signed-off-by: appleboy <appleboy.tw@gmail.com>