Share SciTools/python-stratify#348 `pyproject.toml` improvements via templating?

[scitools-ci]

SciTools/python-stratify#348 (by @HGWright) includes changes to pyproject.toml. This file is not currently templated, but its parent directory suggests it may be a good candidate. Please either:

• Action this issue with a pull request adding a template file to templates/.
• Close this issue if the file is not a good candidate for templating.