pa11y testing tools for Jupyter

This folder contains:

the schema for validating the repos.toml in the root of this repo
a lightwieght server for hosting static HTML sites
- we could use the jupyter server, but don't need/want all the bells and whistles
a minimal (as possible) nodejs environment to run pa11y-ci and its reporters

Future Goals

extract tasks from dodo.py into more configurable, reusable components in this folder
create macros for pa11y actions for common Jupyter tasks
improve reporting, e.g. by collecting all generated reports into an interactive summary Jupyter Notebook/Book
release this capability to an appropriate channel for one-click installation
- ideally PyPI, npmjs.com, conda-forge
  - or if need be, DockerHub, or GitHub Actions