chore: sync pr template from backend

[nibalizer]

Internal Notes for Reviewers

This updates the PR Template per discussion on https://github.com/validmind/backend/pull/1386

External Release Notes

[github-actions]

PR Summary

This pull request updates the GitHub pull request template to include more detailed sections and a comprehensive checklist. The changes aim to improve the clarity and completeness of PR descriptions, ensuring that all necessary information is provided for reviewers and stakeholders.

Key Changes:

• Added sections for describing the change (What), the rationale behind it (Why), and testing instructions (How to Test).
• Introduced a checklist to ensure that all critical aspects of the PR are addressed, including release notes, deployment notes, breaking changes, and testing.
• Removed the chore label from the release notes instructions.
• Added sections for deployment notes, breaking changes, and frontend-specific media (screenshots/videos).
• Included a section for additional notes and areas needing special review.

Test Suggestions

• Verify that the new PR template renders correctly in the GitHub interface.
• Ensure that all new sections in the template are clear and provide the necessary guidance for contributors.
• Check that the checklist items are relevant and comprehensive for typical PRs in the project.
• Test the template by creating a mock PR and filling out each section to ensure usability.

[cachafla]

Great 👌