Suppress a hypothesis HealthCheck on test_split_datasets that fails in nightly CI.

[bdice]

Fixes a HealthCheck error in nightly CI on test_split_datasets:

_____________________________ test_split_datasets ______________________________
[gw0] linux -- Python 3.9.18 /opt/conda/envs/test/bin/python3.9

    @given(split_datasets(standard_datasets()))
>   @settings(suppress_health_check=[HealthCheck.too_slow])
E   hypothesis.errors.FailedHealthCheck: Examples routinely exceeded the max allowable size. (20 examples overran while generating 2 valid ones). Generating examples this large will usually lead to bad results. You could try setting max_size parameters on your collections and turning max_leaves down on recursive() calls.
E   See https://hypothesis.readthedocs.io/en/latest/healthchecks.html for more information about this. If you want to disable just this health check, add HealthCheck.data_too_large to the suppress_health_check settings for this test.

test_strategies.py:101: FailedHealthCheck

Also, from a different run:

FAILED test_strategies.py::test_split_datasets - hypothesis.errors.FailedHealthCheck: Examples routinely exceeded the max allowable size. (20 examples overran while generating 3 valid ones). Generating examples this large will usually lead to bad results. You could try setting max_size parameters on your collections and turning max_leaves down on recursive() calls.

[dantegd]

/merge