Merge pull request #570 from cmu-delphi/sgratzl/prtemplate

chore: add PR template

Author: sgratzl

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,14 @@
+closes <!--list issues closed by this PR -->
+
+**Prerequisites**:
+
+- [ ] Unless it is a documentation hotfix it should be merged against the `dev` branch
+- [ ] Branch is up-to-date with the branch to be merged with, i.e. `dev`
+- [ ] Build is successful
+- [ ] Code is cleaned up and formatted
+
+### Summary
+
+<!--
+  describe what this PR changes
+-->