Update pull_request_template.md to include more details

Signed-off-by: Kevin Yan <[email protected]>

deltacat/.github/pull_request_template.md

@@ -1,7 +1,35 @@
-### Description
-Please describe your pull request.
+## Summary
 
-### Testing checklist
+Briefly describe your changes.
 
-- [ ] Did you write new unit tests?
-- [ ] Did you perform e2e testing and how (e.g. did you run on your personal stack?)
+## Rationale
+
+Explain the reasoning behind the changes and their benefits to the project.
+
+## Changes
+
+List the major changes made in this pull request.
+
+## Impact
+
+Discuss any potential impacts the changes may have on existing functionalities.
+
+## Testing
+
+Describe how the changes have been tested, including both automated and manual testing strategies.
+If this is a bugfix, explain how the fix has been tested to ensure the bug is resolved without introducing new issues.
+
+## Regression Risk
+
+If this is a bugfix, assess the risk of regression caused by this fix and steps taken to mitigate it.
+
+## Checklist
+
+- [ ] Unit tests covering the changes have been added
+  - [ ] If this is a bugfix, regression tests have been added
+
+- [ ] E2E testing has been performed
+
+## Additional Notes
+
+Any additional information or context relevant to this PR.