The `version` parameter is deceptive

[smortex]

The version parameter default to "2.0.0" but is really only used when install_method is changed to "github": in the default configuration the module download and install the latest release of caddy regardless of the value of the version parameter.

Proposal:

• Remove the default version of the parameter and make it optional;
• Report an error when install_method is set to "github" but version is undef.

[smortex]

@AstraLuma @dhoppe maybe?

[AstraLuma]

sounds good, as long as it's documented obviously and has reasonable defaults

[smortex]

My feeling is that 2.0.0 is old and making it mandatory for the user to set the version they want is better. I'll open a PR.