New commits to `pymc3/sampling.py` or `pymc3/step_methods/hmc/`

[github-actions]

This is an auto-generated issue, triggered by the even-with-pymc3 workflow.

There have been new commits to pymc3/sampling.py or pymc3/step_methods/hmc/ since
yesterday: please see the latest run of the even-with-pymc3 GitHub
Action
and consider if these commits are worth mirroring in littlemcmc.

[eigenfoo]

Upstream PR: pymc-devs/pymc#4858

Switches from dill to cloudpickle. This has implications for littlemcmc and we should support this.