Update to latest OpenAI models (#20)

- Introduced new models like 'whisper-1', 'text-davinci-003', 'gpt-4',
'gpt-3.5-turbo-0613', and 'gpt-3.5-turbo-16k-0613'
- Updated permissions for different models, including 'gpt-4-0613',
'ada', 'ada-code-search-code' and 'text-similarity-davinci-001'
- Removed specific outdated models such as 'gpt-3.5-turbo-0301'

Author: blrchen