Added PR checklist (#266)

Author: soumeh01

.github/PULL_REQUEST_TEMPLATE.md

@@ -13,5 +13,9 @@
 
 ## Checklist
 <!-- Put an `x` in the boxes. All tasks must be completed and boxes checked before merging. -->
+- [ ] 🤖 This change is covered by unit tests (if applicable).
+- [ ] 🤹 Manual testing has been performed (if necessary).
+- [ ] 🛡️ Security impacts have been considered (if relevant).
+- [ ] 📖 Documentation updates are complete (if required).
+- [ ] 🧠 Third-party dependencies and TPIP updated (if required).
 
-<!-- TODO: Add a checklist -->