.github/pull_request_template.md

## What changed

<!-- One or two sentences. If this changes what the buddy says or when it says it, say so. -->

## Why

## Checks

- [ ] `pytest` passes
- [ ] `ruff check .` and `ruff format --check .` pass
- [ ] `mypy src/` passes
- [ ] If I changed `perception/captions.py`, I added the caption that motivated it to `tests/test_captions.py`