OPHJOD-166: Add pull request template

Author: ketsappi

.github/pull_request_template.md

@@ -0,0 +1,19 @@
+<!-- Have you ran tests and they pass?
+Did builds complete successfully?
+Remembered to run linters?
+-->
+
+## Description
+
+<!-- Give some description about the PR.
+- What was done and why? Give some context to help the reviewer.
+- Where to focus especially?
+-->
+
+## Related JIRA ticket
+
+<!-- Remember to add link to the JIRA issue
+https://jira.eduuni.fi/browse/OPHJOD-XXX
+-->
+
+https://jira.eduuni.fi/browse/OPHJOD-