chore: update pr template for changelog testing (#6820)

Author: pajlada

.github/pull_request_template.md

@@ -3,3 +3,13 @@
     In the case of a bug fix, please include steps to reproduce the bug so the pull request can be tested.
     If this PR fixes an issue on GitHub, mention this here to automatically close it: "Fixes #1234.".
 -->
+
+<!--
+Leave this at the bottom
+
+Co-authored-by: -
+Tested-by: -
+Reported-by: -
+Reviewed-by: -
+Parent-pr: -
+-->