Reasoner-validator

- Generalize trapi_1.4 testing predicate to trapi_1.4 or later
- biolink:treats as a mixin is tagged as permitted in TRAPI graphs (further code review for this use case is recommended)

- Add back ATTRIBUTE_TYPE_ID_INCLUSIONS filtering for "knowledge_level" and "agent_type" such that the presence of these 'attribute_type_id' values are (blissfully) ignored, conditionally for all Biolink Model releases lower than 4.2.0

- add back in support for Python 3.9

- Reasoner-validator is TRAPI 1.5 aware but nothing more than basic schema validation provided; unit tests which are incompletely refactored are skipped.
- Biolink Model 4.2.0 validation starting to be added : validate presence and values of "knowledge_level" and "agent_type", with compliant values, on all knowledge graph edges (removed previous ATTRIBUTE_TYPE_ID_INCLUSIONS for these fields, since no longer surprising to see them...)
- Update BiolinkValidator.get_result() to properly return Tuple[str, MESSAGES_BY_TARGET]
- Cleaned up some technical debt

- Refactored pyproject.toml specified poetry dependencies into groups rather than extras, updating README accordingly.
- Updated Git action workflows

- Bioregistry "^0.11.1" added as a possible cure for some downstream LinkML issues.
- BMT upgraded to "^1.4.0"