feat: added pull request template (#524)

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,29 @@
+## Description
+
+<!--
+If this is a security issue stop right here and follow our documentation:
+http://docs.django-cms.org/en/latest/contributing/development-policies.html#reporting-security-issues
+-->
+
+## Related resources
+
+<!--
+Add here links to existing issues or conversation from GitHub
+or any other resource.
+-->
+
+* #...
+* #...
+
+## Checklist
+
+<!--
+Please check the following items before submitting, otherwise,
+your pull request will be closed.
+
+Use 'x' to check each item: [x] I have ...
+-->
+
+* [ ] I have added or modified the tests when changing logic
+* [ ] I have followed [the conventional commits guidelines](https://www.conventionalcommits.org/) to add meaningful information into the changelog
+* [ ] I have read the [contribution guidelines ](https://github.com/django-cms/django-cms/blob/develop/CONTRIBUTING.rst)