Dependency versions should not be required

[samj]

We should be able to specify a dependency (e.g., airllm) without needing to arbitrarily specify a version (e.g., 2.8).

Currently when we specify a (Python) dependency, we must include a version:

        "python": [
            {
                "id": "airllm",
                "name": "AirLLM",
                "version": ">=2.8"
            }

If we don't, the backend throws exceptions:

  File "paios/backend/api.py", line 70, in <module>
    version_requirement = dependency['version']
                          ~~~~~~~~~~^^^^^^^^^^^
KeyError: 'version'