v4.1.5

Release Notes:

• Removed the exposed field for configuring the package to use fetch_client instead of http_client manually with is isWeb field, in favor of using dart.library.js and dart.library.io conditional imports to automatically detect the platform and use the appropriate client for it.
• Exposed field for configuring the package to use fetch_client instead of http_client for making requests in web apps (flutter web, etc..)
• Added Audio Speech method in the Audio module with its docs, example code.
• Migrated for the deprecated _functions_and function_call th the use of new fields such tools.. in the chat API, confirmed that it works on both asynchronous and stream responses.
• Exposed API for controlling the requests time out for all internal client methods.
• Exposed multi content calls for chat completion API for image and text..