Add the Pull request template

.github/pull_request_template.md

@@ -0,0 +1,24 @@
+<!-- THE PR TEMPLATE IS NOT AN OPTION. DO NOT DELETE IT, MAKE SURE YOU READ AND EDIT IT! -->
+## Subject
+
+<!-- Describe your Pull Request content here -->
+
+<!--
+    Specify which issues will be fixed/closed.
+    Remove it if this is not related.
+-->
+
+Closes #{put_issue_number_here}.
+
+<!--
+    If this is a work in progress, uncomment the "To do" section.
+    You can add as many tasks as you want.
+    If some are not relevant, just remove them.
+-->
+<!--
+## To do
+
+- [ ] Update the tests;
+- [ ] Update the documentation;
+- [ ] Add an upgrade note.
+-->