chore: add pull-request template

Author: laysakura

pull_request_template.md

@@ -0,0 +1,18 @@
+## Issue number and link
+
+Fixes: #xxx
+
+<!--- For bugfix, you must link to at least an issue to show clear way to reproduce the bug. -->
+
+<!--- For new feature without any related issues, include your motivation in the next section -->
+
+## Describe your changes
+
+## Checklist before requesting a review
+
+- [ ] I follow the [Semantic Pull Requests](https://github.com/zeke/semantic-pull-requests) rules (bugfix/feature)
+- [ ] I specified links to related issues (must: bugfix, want: feature)
+- [ ] I have performed a self-review of my code (bugfix/feature)
+- [ ] I have added thorough tests (bugfix/feature)
+- [ ] I have edited `## [Unreleased]` section in `CHANGELOG.md` following [keep a changelog](https://keepachangelog.com/en/1.0.0/) syntax (bugfix/feature)
+- [ ] I {made/will make} a related pull request for [documentation repo](https://github.com/SpringQL/SpringQL.github.io) (feature)