Issue with mbuild docs

[daico007]

Bug summary

This goes unnoticed for a bit, but it appears that the mbuild docs are not being pushed correctly. The docs build in each PR passes, but the build for new release doesn't, so the docs page still currently showing latest docs for mBuild 0.14.2.

Relevant link:

• https://readthedocs.org/projects/mbuild/builds/
• https://mbuild.mosdef.org/en/stable/

[CalCraven]

Need to add importlib_resources to this file. Potentially gsd is missing as well. https://github.com/mosdef-hub/mbuild/blob/main/docs/docs-env.yml

[daico007]

Fixed by #1169