feat: Add async client

[vblagoje]

Why:

Introduces asynchronous client capabilities to handle OpenAPI interactions for improved performance and scalability. This enhancement addresses the need for async operations when working with APIs in a non-blocking fashion.

• fixes Feature Request: Async suppport #8

What:

• Added AsyncOpenAPIClient: A new asynchronous client class to perform OpenAPI operations.
• Updated README.md: Included documentation and examples for the newly introduced async client patterns.
• Modified dependencies in pyproject.toml to include aiohttp for async HTTP client support.

How can it be used:

The async client can be used in three main ways, as shown in the examples below:

1. Using async context manager:

   async with AsyncOpenAPIClient(config) as service_api:
       service_response = await service_api.invoke(response)

2. Using setup/cleanup explicitly:

   service_api = AsyncOpenAPIClient(config)
   await service_api.setup()
   service_response = await service_api.invoke(response)
   await service_api.cleanup()

3. With a shared aiohttp session:

   async with aiohttp.ClientSession() as session:
       await service_api.setup(session=session)
       service_response = await service_api.invoke(response)

How did you test it:

Unit and integration tests have been added, such as test/test_openapi_client_live_openai_async.py, which validate the async client's ability to handle API interactions under various scenarios, ensuring correct functionality and error handling.

Notes for the reviewer:

Ensure environment variables like OPENAI_API_KEY and SERPERDEV_API_KEY are set for the tests. Focus on the proper handling of async context management and the sessions' lifecycle within the AsyncOpenAPIClient class.

[coveralls]

Pull Request Test Coverage Report for Build 12723623819

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+2.7%) to 84.016%

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Totals
Change from base Build 12712525336:	2.7%
Covered Lines:	410
Relevant Lines:	488

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💛 - Coveralls