🐛 Fix JSON Schema accepting bools as valid JSON Schemas, e.g. `additionalProperties: false` (#9781)
* 🐛 Fix JSON Schema accepting bools as valid JSON Schemas, e.g. additionalProperties: false
* ✅ Add test to ensure additionalProperties can be false
* ♻️ Tweak OpenAPI models to support Pydantic v1's JSON Schema for tuples