openai Python SDK 2.34.0 rejects empty string and None as api_key in AsyncOpenAI constructor

Starting with openai SDK 2.34.0 (released around 2026-05-11), passing api_key="" or api_key=None to AsyncOpenAI() raises openai.OpenAIError: Missing credentials. Previous versions (2.33.0 and earlier) silently accepted these values. This breaks any OpenAI-compatible provider wrapper that intentionally skips API key verification for local servers (e.g., llama.cpp, llamafile, LM Studio, vLLM). Verified by comparing CI runs: openai==2.33.0 passed, openai==2.34.0 failed with identical test code.

When wrapping local or keyless OpenAI-compatible servers, pass a non-empty placeholder string (e.g., "no-key-required") as the api_key to AsyncOpenAI instead of "" or None. The placeholder is never sent over the wire for auth; it only satisfies the SDK's client-side validation. Check the openai SDK changelog for any future changes to credential validation behavior.