Include upgrade test and app updates in release issue template

.gitlab/issue_templates/release.md

 # Release checklist
 
+## Before finalizing release
+
+* [ ] Ensure all applications/dependencies/charts are at their latest versions
+      see `.gitlab/issue_templates/update_all_components.md`
+* [ ] Upgrade test from last version to `master` succeeds
+
 ## In the master branch before releasing
 
 * [ ] Create a MR for the master branch for the following changes: