This commit adds support for Python 3.14 to the library.

The following changes were made:
- Added a 3.14 trove classifier in `setup.py`.
- Added a `grpcio` version constraint for Python 3.14 in `setup.py`.
- Added a 3.14 presubmit configuration file in `.kokoro/samples`.
- Added a `constraints-3.14.txt` file.
- Updated the `CONTRIBUTING.rst` file to include 3.14.
- Updated the `README.rst` file to include 3.14.
- Updated `owlbot.py` to include "3.14" in `unit_test_python_versions`.
- Updated `noxfile.py` to include "3.14" in `UNIT_TEST_PYTHON_VERSIONS` and the `prerelease_deps` session.
- Fixed a flaky test in `tests/unit/pubsub_v1/publisher/test_publisher_client.py`.

This commit adds support for Python 3.14 to the library.

The following changes were made:
- Added a 3.14 trove classifier in `setup.py`.
- Added a `grpcio` version constraint for Python 3.14 in `setup.py`.
- Added a 3.14 presubmit configuration file in `.kokoro/samples`.
- Added a `constraints-3.14.txt` file.
- Updated the `CONTRIBUTING.rst` file to include 3.14.
- Updated the `README.rst` file to include 3.14.
- Updated `owlbot.py` to include "3.14" in `unit_test_python_versions`.
- Updated `noxfile.py` to include "3.14" in `UNIT_TEST_PYTHON_VERSIONS` and the `prerelease_deps` session.
- Fixed a flaky test in `tests/unit/pubsub_v1/publisher/test_publisher_client.py`.
- Added missing configuration files to `.kokoro/samples/python3.14`.

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

This commit adds support for Python 3.14 to the library.

The following changes were made:
- Added a 3.14 trove classifier in `setup.py`.
- Added a `grpcio` version constraint for Python 3.14 in `setup.py`.
- Added a 3.14 presubmit configuration file in `.kokoro/samples`.
- Added a `constraints-3.14.txt` file.
- Updated the `CONTRIBUTING.rst` file to include 3.14.
- Updated the `README.rst` file to include 3.14.
- Updated `owlbot.py` to include "3.14" in `unit_test_python_versions`.
- Updated `noxfile.py` to include "3.14" in `UNIT_TEST_PYTHON_VERSIONS` and the `prerelease_deps` session.
- Fixed a flaky test in `tests/unit/pubsub_v1/publisher/test_publisher_client.py`.
- Added missing configuration files to `.kokoro/samples/python3.14`.
- Fixed an `AttributeError` in `google/cloud/pubsub_v1/subscriber/scheduler.py` that occurred in Python 3.14.

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

This commit adds support for Python 3.14 to the library and drops support for Python 3.7 and 3.8.

The following changes were made:
- Dropped support for Python 3.7 and 3.8 across all configuration files, documentation, and CI/CD pipelines.
- Added a 3.14 trove classifier in `setup.py`.
- Added a `grpcio` version constraint for Python 3.14 in `setup.py`.
- Added a 3.14 presubmit configuration file in `.kokoro/samples`.
- Added a `constraints-3.14.txt` file.
- Updated the `CONTRIBUTING.rst` file to include 3.14 and remove 3.7/3.8.
- Updated the `README.rst` file to include 3.14 and remove 3.7/3.8.
- Updated `owlbot.py` to include "3.14" and remove "3.7"/"3.8" in `unit_test_python_versions`.
- Updated `noxfile.py` to include "3.14" and remove "3.7"/"3.8" in `UNIT_TEST_PYTHON_VERSIONS`.
- Updated `.github/sync-repo-settings.yaml` to include 3.14 and remove 3.7/3.8.
- Removed Kokoro and testing configurations for Python 3.7 and 3.8.
- Fixed a flaky test in `tests/unit/pubsub_v1/publisher/test_publisher_client.py`.
- Fixed an `AttributeError` in `google/cloud/pubsub_v1/subscriber/scheduler.py` that occurred in Python 3.14.

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

Moved the constraints-3.14.txt file from the root directory to the testing/ directory to maintain consistency with other constraint files.