Improve PR template

Use correct checklist syntax

Author: z4y4ts

.github/pull_request_template.md

@@ -1,5 +1,5 @@
-[ ] Add tests for the change. In general, aim for full test coverage at the Python level. Rust tests are optional.
-[ ] Add any appropriate documentation.
-[ ] Add a summary of changes to the `latest` section at the top of `CHANGELOG.rst`. (If it's not there, add it.)
-[ ] Add your name to `AUTHORS.rst`.
-[ ] Run `just full-check`.
+- [ ] Add tests for the change. In general, aim for full test coverage at the Python level. Rust tests are optional.
+- [ ] Add any appropriate documentation.
+- [ ] Add a summary of changes to the `latest` section at the top of `CHANGELOG.rst`. (If it's not there, add it.)
+- [ ] Add your name to `AUTHORS.rst`.
+- [ ] Run `just full-check`.