Flakey test: tests/test_mbrl.py::test_ensemble_training

[tgolsson]

Flaked here: https://buildkite.com/embark-studios/emote/builds/583#018851e0-d12e-4b16-8ed2-a465b479aefb

[spetravic]

Here as well: https://buildkite.com/embark-studios/emote/builds/627