chore: Add PR template checkbox for cross sdk review on public API changes (#5665)

Add PR template checkbox for cross sdk review on public API changes

Author: antonis

.github/pull_request_template.md

@@ -25,6 +25,7 @@
 - [ ] Review from the native team if needed.
 - [ ] No breaking change or entry added to the changelog.
 - [ ] No breaking change for hybrid SDKs or communicated to hybrid SDKs.
+- [ ] Public API changes reviewed by another Mobile SDK team member or implemented according to the [develop docs](https://develop.sentry.dev/) spec.
 
 
 ## :crystal_ball: Next steps