Update .github/PULL_REQUEST_TEMPLATE.md

Author: john0isaac

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,7 +1,7 @@
 # Description
 Please include a summary of the changes and the related issue.
 
-### Checklist
+## Checklist
 - [ ] I have read the contributing guidelines.
 - [ ] I have written tests for the changes, if applicable.
 - [ ] I have added necessary documentation.