git: make style guide a checked requirement

Author: VincentRPS

.github/PULL_REQUEST_TEMPLATE.md

@@ -9,6 +9,7 @@
 - [ ] If code changes were made then they have been tested.
     - [ ] I have updated the documentation to reflect the changes.
 - [ ] If `type: ignore` comments were used, a comment is also left explaining why
+- [ ] This PR follows the commit style on [contributing](https://github.com/pycord-development/pycord/blob/master/.github/CONTRIBUTING.md)
 - [ ] This PR fixes an issue.
 - [ ] This PR adds something new (e.g. new method or parameters).
 - [ ] This PR is a breaking change (e.g. methods or parameters removed/renamed)