chore: Add PII to PR template (#2784)

Author: philipphofmann

.github/pull_request_template.md

@@ -22,6 +22,7 @@
 <!--- Put an `x` in the boxes that apply -->
 - [ ] I reviewed submitted code
 - [ ] I added tests to verify changes
+- [ ] No new PII added or SDK only sends newly added PII if `sendDefaultPII` is enabled
 - [ ] All tests passing
 - [ ] No breaking changes