Notify failed master build + Versioned docs

[jayqi]

Test workflow improvements

• Splits code quality check (linting) into a separate workflow job that runs before tests. If code quality fails, tests do not run.
• Add a workflow job that opens an issue if any previous job fails for non-PR workflows.
• Add workflow_dispatch trigger which enables manually triggering workflow in GitHub UI

Versioned docs using CI

• docs-master will publish to latest version on any merges to master
• release workflow will publish and overwrite any previous docs with same <major>.<minor> version. The new version will also be tagged with (stable) and is assigned the alias stable.

We use latest and stable to refer to master branch and current release, respectively, per Read the Docs naming convention. I've also updated the README badge to say "stable" instead of "latest".

All docs are stored on the gh-pages branch, and the workflows will push that branch to Netlify. I've manually backfilled existing releases. This won't be pushed to Netlify until the PR is merged. In the meantime, you can see https://erdantic.drivendata.org/ as an example.

PR previews continue to work as-is without integration with the other versions.

[jayqi]

Tests failing due to #76

[codecov[bot]]

Codecov Report

Merging #75 (4656636) into master (fa4c80c) will not change coverage. The diff coverage is n/a.

@@          Coverage Diff           @@
##           master     #75   +/-   ##
======================================
  Coverage    98.1%   98.1%           
======================================
  Files           8       8           
  Lines         382     382           
======================================
  Hits          375     375           
  Misses          7       7           

[github-actions[bot]]

🚀 Deployed on https://deploy-preview-75--zen-roentgen-1e5a72.netlify.app