Story #4687: As a user, I can use either Python or Ruby bindings to interact with Pulp
switch pulp-swagger-codegen to openapi-generator
swagger-codegen has been forked by it's original authors and now releases under the name openapi-generator. It looks like this project releases much more frequently than swagger-codegen. It's a drop in replacement so we should switch to it to resolve the python 3.7 incompatibility problem in the bindings.