Fix bug in gpt-service.js that happens in function calls

[akiani]

The order of parameters was wrong, causing OpenAI API to give an error because the function name was being passed instead of the role. Simply reordering the parameters would fix this issue (currently only happens in the transferCall function)

Contributing to Twilio

All third-party contributors acknowledge that any contributions they provide will be made under the same open-source license that the open-source project is provided under.

• [X] I acknowledge that all my contributions will be made under the project's license.