Add test for openvox requirement

[bastelfreak]

This test ensures that we can list openvox as a requirement in metadata.json. It's valid with and without puppet:

"requirements": [
  {
    "name": "puppet",
    "version_requirement": ">= 7.0.0 < 9.0.0"
  },
  {
    "name": "openvox",
    "version_requirement": ">= 7.0.0 < 9.0.0"
  }
]

"requirements": [
  {
    "name": "openvox",
    "version_requirement": ">= 7.0.0 < 9.0.0"
  }
]

[ekohl]

Is there any document we can refer to that describes this?

[bastelfreak]

Not as far as I know yet. I just wanted to ensure that the linter actually allow multiple requirements and not only puppet.