Release 0.3.1

[bollwyvl]

• [x] blockers
  • [x] #38 fix docs build
  • [x] #33 mystnb/pydata-sphinx-theme
  • [x] #36 add some backwards-compatible options for interacting with multiple notebooks in Lab
  • [x] #37 add some more timeout args
  • [x] maybe add some more in some places where we hard-code them
• [x] infra
  • [x] resolve envs
  • [x] validate on binder
  • [x] tag
  • [x] upload
  • [x] pypi
  • [x] postmortem
  • [x] conda-forge
  • [x] update release process notes