Deploy on CI

[mottosso]

@monkeez I've moved CI from Azure to GitHub Actions, since Azure wasn't playing ball anymore. It wasn't providing a good UI on GitHub either, making it hard to spot when and where things went wrong.

The documentation deployment got lost in the transition, and there are a few too many things I don't recognise in the setup. Would you happen to have a moment to see if you can port it over?

  # -----------------------------------------------------------------------
  #
  # Deploy docs
  #
  # -----------------------------------------------------------------------

  - job: Deploy_Docs
    condition: startsWith(variables['Build.SourceBranch'], 'refs/tags')
    pool:
      vmImage: "ubuntu-latest"
    steps:
      - task: DownloadPipelineArtifact@2
        inputs:
          artifact: docs
          path: $(Build.SourcesDirectory)/build/html

      - script: |
          git init
          git config --local user.name "Azure Pipelines"
          git config --local user.email "mitchellcoote@gmail.com"
          git add .
          touch .nojekyll
          git add .nojekyll
          git commit -m "Commit generated documentation"
        displayName: "Commit pages"
        workingDirectory: build/html

      - task: InstallSSHKey@0
        inputs:
          knownHostsEntry: $(KNOWN_HOST)
          sshKeySecureFile: deploy_key

      - script: |
          git remote add origin git@github.com:mottosso/cmdx.git
          git push -f origin HEAD:gh-pages
        displayName: "Publish GitHub Pages"
        workingDirectory: build/html

    dependsOn: Maya

I think it's safe to write as a separate "workflow" that only triggers on tags, similar to the PyPI deployment workflow currently in place.

[monkeez]

I'll will try find some time to look into it, might be a couple of weeks though.