docs: create pull_request_template.md

[mhoff]

Description

• Quickly summarize your changes in a few bullet points (can and should correspond to CHANGELOG.md)
• Fixes #XXX (insert issue number here), if there is a corresponding GH issue

Assignee

• The changes adhere to the contribution guidelines
• I have performed a self-review of my code
• My changes generate no new warnings

Documentation

• README.md is up-to-date
• CHANGELOG.md is up-to-date
• Sources for readthedocs are up-to-date
• Notebooks are up-to-date and functional
• Examples are up-to-date and functional (including compose & k8s)

Code Quality

• Patch test coverage > 95%
• New code uses correct & specific type hints

How did you verify that the changes actually work in-practice?

• List of (preferably easy reproducible) tests including OS

Reviewer

• The code is readable/maintainable and follows the contribution guidelines
• Documentation is up-to-date