Adding in pull request template

[zeerekahmad]

Description

Pull Request Template from polymath_core is brought over as standard for polymath_kinematics

Migration Guide

n/a

Related issues

n/a

Completeness checklist

• Is there test coverage? If it was a bugfix, is there a regression test?
• Is user-facing API/behavior documented?
• Is core documentation updated?
• Are all checks green?
• Assign reviewers to the PR and post in #code_reviews

---

_{Stack created with GitHub Stacks CLI • Give Feedback 💬}