Rename repository to support packer init

[F21]

In order to use this plugin with packer init, the repository name must be packer-plugin-goss.

Further information here: https://developer.hashicorp.com/packer/docs/plugins/install-plugins#installation-guides

This will allow us to include the plugin in required_plugins like this:

packer {
  required_plugins {
    goss = {
      version = "~> 3.1"
      source  = "github.com/YaleUniversity/goss"
    }
  }
}

With the current repo name, we get the following error when running packer init:

$ packer init .
Failed getting the "github.com/yaleuniversity/goss" plugin:
1 error occurred:
        * GET https://api.github.com/repos/yaleuniversity/packer-plugin-goss/git/matching-refs/tags: 404 Not Found []

This issue should resolve and supercede #65

[F21]

Duplicated by #58