[DOC] add pr template

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,13 @@
+# What does this PR do?
+<!--- Provide a general summary of your changes in the Title above. -->
+
+<!-- Replace this with a description of the change and which issue is fixed (if applicable). Please also include relevant motivation and context. List any dependencies (if any) that are required for this change. -->
+
+## Pre-Submission Checklist
+<!---  Put an `x` in the boxes as follows. --->
+- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
+- [ ] Have you followed the commit format and enabled the pre-commit process as outlined in the [developer guide](https://github.com/Learnware-LAMDA/Learnware/blob/main/docs/about/dev.rst)?
+- [ ] Was this discussed/approved via a Github issue? Please provide a link
+      to the issue.
+- [ ] Did you pass the test by running `pytest tests/test_workflow` in the root directory?
+- [ ] If adding a new feature, have you added tests that cover your changes?