- Add a new job `testing-with-env` to the GitHub Actions workflow
- Add steps to set up environment variables for public and private SSH keys
- Add a step to create a new SSH server using Docker
- Add a step to test the SSH connection using the `id_ed25519` key
- Add a step to pass a single environment variable to the SSH action
- Add a step to pass multiple environment variables to the SSH action
- Add a step to use a custom format for environment variables
- Add a step to pass all environment variables to the SSH action
Signed-off-by: appleboy <appleboy.tw@gmail.com>