Enhance template

Signed-off-by: Ambika Nair <[email protected]>

Author: ambiknai

template/pull_request_template.md

@@ -5,4 +5,5 @@
 ## Checklist before requesting a review
 - [ ] I have performed a self-review of my code
 - [ ] If it is a core feature, I have added thorough tests.
+- [ ] I have made sure existing UTs are not impacted
 - [ ] I have executed all necessary linter and made sure internal pipeline/travis is not broken