Maintenance cleanup

[timbernat]

Description

Improve automated testing and deployment, while cleaning up some minor cosmetic defects

Todos

Notable points that this PR has either accomplished or will accomplish.

• Add polythiophene helix image as logo asset to docs
• Fix malformatted OpenFF link in installation instructions
  • Rebuild docs to verify fix is reflected before merging
• Incorporate nbval notebook testing automation
  • Write series-specific and master nbval scripts
  • Add Exception/Skip etc. directives where applicatble to examples
  • Include nbval in test-env.yml reqs
  • Add clause to CI.yaml to run notebooks tests after local unit tests run
  • Configure notebook tests to bubble up failure thru CI runs
  • Configure OpenMM runs more intelligently to prevent CI runs from taking too long
• CI Updates
  • Create action for automated GH deployment to PyPI on new release
  • Update Codecov report + token in CI action

Status

• Pass new CI tests
• Ready to go

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