InvokeAI/.github/pull_request_template.md

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## Summary

<!--A description of the changes in this PR. Include the kind of change (fix, feature, docs, etc), the "why" and the "how". Screenshots or videos are useful for frontend changes.-->

## Related Issues / Discussions

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## QA Instructions

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## Merge Plan

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## Checklist

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- [ ] The PR has a short but descriptive title
- [ ] Tests added / updated
- [ ] Documentation added / updated