This PR fixes two issues causing CI failures:
1. **Boolean Round Trip**: Adjusted the expected DataFrame in
`test_dataframe_round_trip_with_table_schema` to correctly handle
`pd.NA` returned by the connector for nullable boolean values, instead
of `None`.
2. **CSV Extreme Datetimes**: Implemented `cast_dataframe_for_csv` to
pre-format `DATETIME` and `TIMESTAMP` columns using `.isoformat()`
before CSV serialization. This ensures years before 1000 are zero-padded
(e.g., `0001-01-01`), avoiding invalid date string errors from BigQuery
when loading data.


---
*PR created automatically by Jules for task
[5793097527839411486](https://jules.google.com/task/5793097527839411486)
started by @chalmerlowe*

---------

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Co-authored-by: chalmer lowe <[email protected]>

This PR effectively moves ownership for this repo to the python language team, and removes api-bigquery as the defacto code owner.

This PR adds support for Python 3.14 to the library.

   Key changes include:
- Adding Python 3.14 to the test matrix in
`.github/workflows/unittest.yml`.
   - Updating `setup.py` to include the Python 3.14 classifier.
   - Adding `testing/constraints-3.14.txt`.
- Updating `noxfile.py` to include 3.14 sessions, and set default to
3.14.
- Updating `CONTRIBUTING.rst` to list Python 3.14 as a supported
version.

NOTE: The Kokoro Samples 3.14 check will fail. The docker container for
running that session does not yet have Python 3.14 in it. That is being
done in parallel. The fact that the Samples check does not pass should
not prevent this from being merged.
NOTE: tweaked a set of tests to no longer use pytz which was a transient
dependency in the past but the library that used to install with it no
longer does. Moved timezone info from pytz to the standard library's
timezone module.

---------

Co-authored-by: ohmayr <[email protected]>
Co-authored-by: Tim Sweña (Swast) <[email protected]>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Co-authored-by: Chalmer Lowe <[email protected]>

PR created by the Librarian CLI to initialize a release. Merging this PR
will auto trigger a release.

Librarian Version: v0.7.0
Language Image:
us-central1-docker.pkg.dev/cloud-sdk-librarian-prod/images-prod/python-librarian-generator@sha256:c8612d3fffb3f6a32353b2d1abd16b61e87811866f7ec9d65b59b02eb452a620
<details><summary>pandas-gbq: 0.32.0</summary>

##
[0.32.0](v0.31.1...v0.32.0)
(2025-12-15)

### Features

* Add support for Python 3.14 (#976)
([89b008d](89b008d8))

### Bug Fixes

* boolean round-trip test and CSV datetime loading errors (#1000)
([d443103](d4431030))

</details>