Added PR template. The madness with empty PR description must stop

Author: oleksandr-pavlyk

.github/pull_request_template.md

@@ -0,0 +1,5 @@
+- [ ] Have you provided a meaningful PR description?
+- [ ] Have you added a test, reproducer or referred to issue with a reproducer?
+- [ ] Have you tested your changes locally for CPU and GPU devices?
+- [ ] Have you made sure that new changes do not introduce compiler warnings?
+- [ ] If this PR is a work in progress, are you filing the PR as a draft?