ssh_password should not be required

[alkalinecoffee]

When configuring ssh config w/ this plugin on AWS, we get the following error if ssh_password is omitted:

Error: module.ami.data.packer_json.config: "builders.0.amazon_ebs.0.ssh.0.ssh_password":
required field is not set

To get around this, we just set a dummy ssh_password value. This value is not required by packer.

Thanks for this plugin by the way, it'll really help out our team! 🍺