warnings in ibis 3.x test suite

[tswast]

https://github.com/ibis-project/ibis-bigquery/runs/6531971855?check_suite_focus=true

ibis_bigquery/tests/system/test_compiler.py:6
  /home/runner/work/ibis-bigquery/ibis-bigquery/ibis_bigquery/tests/system/test_compiler.py:6: PytestUnknownMarkWarning: Unknown pytest.mark.bigquery - is this a typo?  You can register custom marks to avoid this warning - for details, see https://docs.pytest.org/en/stable/how-to/mark.html
    pytestmark = pytest.mark.bigquery

tests/system/test_client.py::test_exists_table
tests/system/test_client.py::test_exists_table_different_project
tests/system/test_client.py::test_exists_table_different_project_fully_qualified
  /home/runner/.local/lib/python3.8/site-packages/ibis_bigquery/__init__.py:308: FutureWarning: `client.exists_table(name)` is deprecated, and will be removed in a future version of Ibis. Use `name in client.list_tables()` instead.
    warnings.warn(

tests/system/test_client.py::test_exists_database
tests/system/test_client.py::test_exists_database_different_project[bigquery-public-data.epa_historical_air_quality-True]
tests/system/test_client.py::test_exists_database_different_project[bigquery-foo-bar-project.baz_dataset-False]
  /home/runner/.local/lib/python3.8/site-packages/ibis_bigquery/__init__.py:285: FutureWarning: `client.exists_database(name)` is deprecated, and will be removed in a future version of Ibis. Use `name in client.list_databases()` instead.
    warnings.warn(

tests/system/test_client.py::test_exists_database
tests/system/test_client.py::test_exists_database
tests/system/test_client.py::test_exists_database_different_project[bigquery-public-data.epa_historical_air_quality-True]
tests/system/test_client.py::test_exists_database_different_project[bigquery-foo-bar-project.baz_dataset-False]
  /home/runner/.local/lib/python3.8/site-packages/ibis_bigquery/__init__.py:294: PendingDeprecationWarning: Client.dataset is deprecated and will be removed in a future version. Use a string like 'my_project.my_dataset' or a cloud.google.bigquery.DatasetReference object, instead.
    dataset_ref = client.dataset(dataset, project=project)

tests/system/test_client.py::test_cross_project_query
  /home/runner/work/ibis-bigquery/ibis-bigquery/ibis_bigquery/tests/system/test_client.py:524: DeprecationWarning: `np.object` is a deprecated alias for the builtin `object`. To silence this warning, use `object` by itself. Doing this will not modify any behavior and is safe. 
  Deprecated in NumPy 1.20; for more details and guidance: https://numpy.org/devdocs/release/1.20.0-notes.html#deprecations
    assert df.title.dtype == np.object

tests/system/udf/test_udf_execute.py: 14 warnings
  /home/runner/.local/lib/python3.8/site-packages/ibis_bigquery/udf/__init__.py:186: FutureWarning: `Argument` is deprecated as of v3.0; use Validator if needed
    (name, Arg(rlz.value(type)))