Fix Celery worker crash on Airflow 3.0 with json_logs

[vatsrahul1001]

What

The Celery worker CLI passes json_output to airflow.sdk.log.configure_logging under an AIRFLOW_V_3_0_PLUS gate (added in #68916 "Honor json_logs config in Celery worker startup"):

if AIRFLOW_V_3_0_PLUS:
    from airflow.sdk.log import configure_logging
    ...
    configure_logging(output=sys.stdout.buffer, json_output=json_output)

But json_output was only added to the Task SDK's configure_logging in SDK 1.1 / Airflow 3.1 (the structlog migration, #52651). On Airflow 3.0.x that parameter does not exist, so the call raises:

TypeError: configure_logging() got an unexpected keyword argument 'json_output'

…and the Celery worker crashes on startup. The AIRFLOW_V_3_0_PLUS gate is too loose — this affects any plain Airflow 3.0.x deployment running celery provider >= 3.22.0.

How

• Add an AIRFLOW_V_3_1_PLUS constant to the provider's version_compat.
• Gate the json_logs handling on AIRFLOW_V_3_1_PLUS. On Airflow 3.0.x, fall back to configure_logging(output=sys.stdout.buffer) (no json_output), matching the pre-Honor json_logs config in Celery worker startup #68916 behavior.

This keeps the provider compatible across the full Airflow 3.x range it declares support for; json_logs is honored from 3.1+ where the SDK supports it.

Tests

Added test_json_output_not_passed_on_airflow_3_0 (patches AIRFLOW_V_3_1_PLUS = False, asserts configure_logging is called without json_output). Existing json_logs tests continue to assert the 3.1+ behavior.

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Was generative AI tooling used to co-author this PR?

• Yes (Claude Code)

Generated-by: Claude Code (Opus 4.8) following the guidelines

I reviewed and understand all of the generated code, verified it against the actual worker() code path, and ran the relevant static checks and tests locally.

[kaxil]

LGTM. Correct version boundary -- verified against stable-branch content that json_output lands in the task-sdk configure_logging on 3.1+, so gating the 3.0.x fallback on AIRFLOW_V_3_1_PLUS is right. Fix restores pre-#68916 behavior and the regression test has teeth.