docs(github): add pull request template

.github/pull_request_template.md

@@ -0,0 +1,7 @@
+<!--
+  Please follow the Conventional Commits specification.
+
+  If you need to update your PR with changes from `master`, please run `git rebase master`.
+
+  By opening this PR, you confirm that you have read and understood this project's `CONTRIBUTING.md`.
+-->