google-cloud-bigquery: python-dateutil <3.0.0 constraint blocks upgrade to 3.0.0 #18806

Summary

Upgrading python-dateutil from 2.9.0.post0 to 3.0.0 causes dependency resolution to fail with google-cloud-bigquery==3.46.2. The resolver reports that BigQuery requires python-dateutil>=2.8.2,<3.0.0.

Could you evaluate support for python-dateutil 3.0 and relax the upper bound if compatible, or clarify which incompatibility requires the restriction?

API client name and version

google-cloud-bigquery==3.46.2

Environment

• GitHub Actions, Linux and Windows runners
• CPython 3.15.1
• Dependency manager: uv
• Both installation jobs fail before application code or tests run.

Relevant requirements

google-cloud-bigquery==3.46.2
python-dateutil==3.0.0

These are the conflicting requirements extracted from our application's dependency set, rather than a separately tested minimal reproduction.

Our Linux CI command is uv sync --locked. The Windows job adds wheel-validation flags unrelated to this version conflict; both jobs produce the same dependency-resolution error.

Actual result: exact error from CI

error: No solution found when resolving dependencies
  cause: Because google-cloud-bigquery>=3.46.2 depends on python-dateutil>=2.8.2,<3.0.0 and your project depends on google-cloud-bigquery==3.46.2, we can conclude that your project depends on python-dateutil>=2.8.2,<3.0.0.
         And because your project depends on python-dateutil==3.0.0, we can conclude that your project's requirements are unsatisfiable.

This error was observed on both platforms on 22 October 2026. We have retained python-dateutil 2.9.0.post0 as a workaround.

Expected result

If the library is compatible with python-dateutil 3.0, allow the dependency combination to resolve. Otherwise, guidance on the incompatibility or a tracking issue for support would help downstream projects plan the upgrade. This report concerns the dependency constraint; it does not claim that runtime compatibility with dateutil 3.0 has been verified.

Additional context

I searched this repository for a matching issue and did not find one. PR #18798 updates python-dateutil in packages/google-cloud-bigquery/samples/geography/requirements.txt, but does not change the library's dependency metadata.