Update PyPI package docs to current recommendation

Merged Laurie O requested to merge Epic_Wink/gitlab:pypi-pyproject into master

What does this MR do?

Updates the package-creation tutorial in the PyPI documentation to the current recommendation from the Python packaging community.

The current recommendation is to use the latest standards, which include specifying the build-backend and project metadata in pyproject.toml. This change makes the decision to stick with setuptools.

Author's checklist

Reviewer's checklist

Documentation-related MRs should be reviewed by a Technical Writer for a non-blocking review, based on Documentation Guidelines and the Style Guide.

  • If the content requires it, ensure the information is reviewed by a subject matter expert.
  • Technical writer review items:
    • Ensure docs metadata is present and up-to-date.
    • Ensure the appropriate labels are added to this MR.
    • Ensure a release milestone is set.
    • If relevant to this MR, ensure content topic type principles are in use, including:
      • The headings should be something you'd do a Google search for. Instead of Default behavior, say something like Default behavior when you close an issue.
      • The headings (other than the page title) should be active. Instead of Configuring GDK, say something like Configure GDK.
      • Any task steps should be written as a numbered list.
      • If the content still needs to be edited for topic types, you can create a follow-up issue with the docs-technical-debt label.
  • Review by assigned maintainer, who can always request/require the reviews above. Maintainer's review can occur before or after a technical writer review.
Edited by Laurie O