Update PR template (#618)

* Add PR template

Co-authored-by: Dom Heinzeller <[email protected]>

.github/pull_request_template.md

@@ -0,0 +1,28 @@
+### Summary
+
+Describe the changes made in this PR and why they are needed.
+
+### Testing
+
+Describe the testing done for this PR.
+
+### Applications affected
+
+List all known applications (UFS WM, JEDI, SRW, etc.) intentionally or unintentionally affected by this PR.
+
+### Systems affected
+
+List all systems intentionally or unintentionally affected by this PR.
+
+### Dependencies
+
+If there are PRs that need to be merged before or along with this one, please add "- [ ] waiting on LINK_TO_PR" for each of them
+
+### Issue(s) addressed
+
+Link the issues addressed or resolved by this PR (use `Fixes #???` for fully resolved issues)
+
+### Checklist
+- [ ] This PR addresses one issue/problem/enhancement, or has a very good reason for not doing so.
+- [ ] These changes have been tested on the affected systems and applications.
+- [ ] All dependency PRs/issues have been resolved and this PR can be merged.