Python SDK: no PyPI release since June 3 — bundled runtime (0.137.0a4) doesn't expose GPT-5.6 models

What issue are you seeing?

The Python SDK on PyPI has been static for ~5 weeks while the CLI moved on: the last uploads are openai-codex 0.1.0b3 and openai-codex-cli-bin 0.137.0a4, both from June 3, while the CLI is at rust-v0.144.1 (July 9). On the bundled 0.137 runtime, the GPT-5.6 family (GA July 9) never appears, so SDK users can't reach the current models.

What steps can reproduce the bug?

pip install openai-codex==0.1.0b3
python -c "import asyncio; from openai_codex import AsyncCodex
async def m():
    async with AsyncCodex() as c:
        page = await c.models()
        print([m.id for m in page.data])
asyncio.run(m())"
# → ['gpt-5.5', 'gpt-5.4', 'gpt-5.4-mini']   (no gpt-5.6 family)

What is the expected behavior?

A new SDK beta pinning a runtime ≥ 0.144 so models() exposes the GPT-5.6 family. (Third-party reporting suggests 5.6 is only served to CLI ≥ 0.144, which would match what we observe.)

Additional information

sdk/python on main is actively developed (commits through July 6), just unreleased. Staying pinned this far back also re-exposes deserialization skew like #21871 (still open).