fix(retry): retry on aiohttp and google-auth timeout exceptions with HttpRetryOptions - #3330

Closes #3329.

Summary

When HttpRetryOptions is configured and aiohttp is active (google-genai[aiohttp]), transient request timeouts and google.auth.aio-wrapped transport errors bypassed retry_args() and surfaced on the first attempt.

• Add asyncio.TimeoutError (which also covers aiohttp.ServerTimeoutError and aiohttp.ConnectionTimeoutError) and google.auth.exceptions.TimeoutError (raised by google.auth.aio.transport.aiohttp.Request and AsyncAuthorizedSession.request on timeout) to _AIOHTTP_TRANSIENT_EXC, matching httpx.TimeoutException in _HTTPX_TRANSIENT_EXC (httpx.TimeoutException is not retried despite HttpRetryOptions being configured #2337 / fix(retry): retry on httpx.TimeoutException with HttpRetryOptions #2345).
• In retry_args(), also match google.auth.exceptions.TransportError when e.__cause__ is an instance of _AIOHTTP_TRANSIENT_EXC, aligning retry_args() with _async_request_once()'s except (..., auth_exceptions.TransportError): raise # HttpRetryOptions owns retries; tenacity decides while keeping non-transient errors (aiohttp.ClientPayloadError, google.auth.exceptions.RefreshError) non-retriable.
• Keep the default behavior when HttpRetryOptions is unset unchanged (client-side timeouts are not implicitly retried without retry_options).
• Add unit tests in google/genai/tests/client/test_aiohttp_retries.py covering retry_args() predicates and async_request() retry behavior for asyncio.TimeoutError and google.auth.exceptions.TimeoutError.

Testing

$ pytest google/genai/tests/client/test_aiohttp_retries.py google/genai/tests/client/test_retries.py -q
53 passed in 30.13s

$ mypy google/genai/_api_client.py
Success: no issues found in 1 source file

$ git diff --check