Update pull_request_template.md (#48805)

Release Notes:

- N/A

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Co-authored-by: Lena <241371603+zelenenka@users.noreply.github.com>

.github/pull_request_template.md

@@ -1,8 +1,9 @@
 Closes #ISSUE
 
-- [ ] Tests or screenshots needed?
-- [ ] Code Reviewed
-- [ ] Manual QA
+Before you mark this PR as ready for review, make sure that you have:
+- [ ] Added a solid test coverage and/or screenshots from doing manual testing
+- [ ] Done a self-review taking into account security and performance aspects
+- [ ] Aligned any UI changes with the [UI checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
 
 Release Notes: