Strict Response Validation doesn't enforce status codes from schema

[mjmccain52]

Description

Our openapi schema had for a certain endpoint defined expected responses for 201, 400, 401, and 500 status codes.
The 201 was actually a copy paste typo, and we were returning a 200.
Because the schema for 200 was undefined, no validation occurred.
Strict validation and Response validation were both set to true.

Expected behaviour

An undocumented status code should result in validation failure and a 500

Actual behaviour

An undocumented status code skips response validation

Steps to reproduce

• Create a connexion flask app configured with both strict_validation and validate_responses set to True, and also using an openapi.yaml schema
• inside the schema, define a basic endpoint path with a acceptable responses set to 201 and create a basic schema to validate
• inside the flask app, have the endpoint return a response body that breaks the schema, but with a 200 status code