Improve the details of simulator specification errors

[jonrkarr]

The validator returns this

{
  "error": [
    {
      "status": "400",
      "title": "ValidatorError",
      "detail": "Algorithms must be annotated with unique KiSAO terms",
      "source": {
        "pointer": "/algorithms"
      }
    }
  ]
}

However, the test suite displays this

- Simulator specifications from https://raw.githubusercontent.com/biosimulators/Biosimulators_VCell/00d08a031a0788435b44989e73ae3f43f33e4cb0/biosimulators.json are not valid. Specifications must be adhere to the BioSimulators schema. Documentation is available at https://api.biosimulators.org/.
- 
-   400 Client Error: Bad Request for url: https://api.biosimulators.org/simulators/validate

The test suite should display the source and detail attributes from the validator's response.

[jonrkarr]

done