Resolve CI failures with main branch

[seratch]

With recent realtime module related code additions, the current main branch fails due to test coverage (93%, which misses 95% target). This prevents new contributions. We can add tests and hit 95% later on, but for now, changing the config should be a reasonable choice.

[seratch]

The old_versions test failure looks another issue:

============================= test session starts ==============================
platform linux -- Python 3.9.23, pytest-8.3.5, pluggy-1.5.0
rootdir: /home/runner/work/openai-agents-python/openai-agents-python
configfile: pyproject.toml
plugins: inline-snapshot-0.22.3, mock-3.14.0, asyncio-0.26.0, anyio-4.9.0
asyncio: mode=auto, asyncio_default_fixture_loop_scope=session, asyncio_default_test_loop_scope=function
collected 397 items / 2 errors

═══════════════════════════════ inline-snapshot ════════════════════════════════
INFO: CI run was detected because environment variable "CI" was defined.
INFO: inline-snapshot runs with --inline-snapshot=disabled by default in CI.

==================================== ERRORS ====================================
________________ ERROR collecting tests/realtime/test_agent.py _________________
tests/realtime/test_agent.py:4: in <module>
    from agents.realtime.agent import RealtimeAgent
src/agents/realtime/__init__.py:2: in <module>
    from .config import APIKeyOrKeyFunc
src/agents/realtime/config.py:74: in <module>
    APIKeyOrKeyFunc = str | Callable[[], MaybeAwaitable[str]]
E   TypeError: unsupported operand type(s) for |: 'type' and '_CallableGenericAlias'
___________ ERROR collecting tests/realtime/test_transport_events.py ___________
tests/realtime/test_transport_events.py:3: in <module>
    from agents.realtime.transport_events import RealtimeTransportEvent
src/agents/realtime/__init__.py:2: in <module>
    from .config import APIKeyOrKeyFunc
src/agents/realtime/config.py:74: in <module>
    APIKeyOrKeyFunc = str | Callable[[], MaybeAwaitable[str]]
E   TypeError: unsupported operand type(s) for |: 'type' and '_CallableGenericAlias'
=========================== short test summary info ============================
ERROR tests/realtime/test_agent.py - TypeError: unsupported operand type(s) for |: 'type' and '_CallableGenericAlias'
ERROR tests/realtime/test_transport_events.py - TypeError: unsupported operand type(s) for |: 'type' and '_CallableGenericAlias'
!!!!!!!!!!!!!!!!!!! Interrupted: 2 errors during collection !!!!!!!!!!!!!!!!!!!!
============================== 2 errors in 1.36s ===============================
make: *** [Makefile:43: old_version_tests] Error 2
Error: Process completed with exit code 2.

https://github.com/openai/openai-agents-python/actions/runs/16231269681/job/45834418871?pr=1077

[seratch]

Resolved all the failures:

• test coverage requirements: 95 -> 90 (currently 93)
• modify some of the added realtime module code to be compatible with python 3.9

[rm-openai]

I'm just going to fix forward - I wanted to merge bc it's a pain to add tests to a large PR, but I want to fix by EOD

[seratch]

OK, thanks!