chore: create pull_request_template.md (#2418)

.github/pull_request_template.md

@@ -0,0 +1,12 @@
+## Summary
+<!-- Briefly describe the changes -->
+
+## Rationale
+<!-- Why are these changes necessary? -->
+
+## How has this been tested?
+- [ ] Current tests cover my changes
+- [ ] Added new tests
+- [ ] Manually tested the code
+
+<!-- Describe the steps you've taken to verify the changes -->