feat: edit PR template

Author: fumiama

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,7 +1,7 @@
 # Pull request checklist
 
 - [ ] The PR has a proper title. Use [Semantic Commit Messages](https://seesparkbox.com/foundry/semantic_commit_messages). (No more branch-name title please)
-- [ ] Make sure you are requesting the right branch.
+- [ ] Make sure you are requesting the right branch: `dev`.
 - [ ] Make sure this is ready to be merged into the relevant branch. Please don't create a PR and let it hang for a few days.
 - [ ] Ensure all tests are passing.
 - [ ] Ensure linting is passing.