[v3.x] Update pull_request_template.md (#8407)

* Update pull_request_template.md

Adding diagnostic events reminder to checklist.

* Update pull_request_template.md

Requested changes.

Co-authored-by: Katy Shimizu <[email protected]>

Author: github-actions[bot]

.github/pull_request_template.md

@@ -12,6 +12,8 @@ resolves #issue_for_this_pr
     * [ ] Otherwise: I've added my notes to `release_notes.md`
 * [ ] My changes **do not** need to be backported to a previous version
     * [ ] Otherwise: Backport tracked by issue/PR #issue_or_pr
+* [ ] My changes **do not** require diagnostic events changes
+    * Otherwise: I have added/updated all related diagnostic events and their documentation (Documentation issue linked to PR)
 * [ ] I have added all required tests (Unit tests, E2E tests)
 
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