Clean up pull request template
-# Description
+#### Description
<!-- Please include a summary of the change and which issue is fixed. -->
Fixes # (issue)
-### Checklist:
+#### Checklist:
- [ ] I have ran `./ci/run_stable_checks.sh`
- [ ] I have performed a self-review of my own code
-- [ ] I have added tests that prove my fix is effective or that my feature works -->
+- [ ] I have added tests that prove my fix is effective or that my feature works
<!-- Performance Improvements Only -->
<!-- 1. Fork and clone https://github.com/yewstack/js-framework-benchmark -->
