Validator only catches the first validation error

[a-berish]

Describe the bug
The Validator class only catches the first invalid element within a resource JSON file.

To Reproduce
Steps to reproduce the behavior:
Run after #23 is complete and PR is merged.

Expected behavior
The validator should continue validating after an invalid element is found. If there is more than one validation error, the validation error messages should be combined and added to the returned explanation.

Additional context
Consider using iter_errors to list all errors within a single resource JSON file.

• https://stackoverflow.com/questions/52196407/show-all-errors-in-json-schema-using-json-validate-using-python
• https://python-jsonschema.readthedocs.io/en/stable/validate/#jsonschema.protocols.Validator.iter_errors