Introduce GitHub Action to install project requirements

[rmartin16]

Changes

• Introduces composite action to install specific requirements from a project's pyproject.toml

PR Checklist:

• All new features have been tested
• All new features have been documented
• I have read the CONTRIBUTING.md file
• I will abide by the code of conduct

[freakboy3742]

All looks fairly straightforward; two suggestions around argument handling that might help avoid surprises in the future.

[freakboy3742]

Checking that I'm reading this right - if you don't specify extra as an argument, this manifests as --extra "" in the final arguments, right? Would it be worth gating the --extra argument with an if inputs.extra?

[rmartin16]

The default value of extra within the install_requirement.py script is an empty string. So, passing --extra an empty string at the command-line is equivalent to not specifying --extra at all. With that, we can control specifying --extra at the command-line but it's effectively duplicating effort the script already handles.

[rmartin16]

That said...

         python -m install_requirement ${{ inputs.requirements }} \
-          --extra "${{ inputs.extra }}" \
+          ${{ inputs.extra && format('--extra {0}', inputs.extra) || '' }} \
           --project-root "$(printf -- "%q" "${{ steps.paths.outputs.project-root }}")"

[freakboy3742]

👍