feat: add renovate to repo

[JossWhittle]

🚧 Suggest a change

Add workflow to run renovate on the repo.

📝 Pre-merge checklist

Ready to merge? Do not merge until all checks are satisfied.

• 💹 Have all required CI checks passed on the most recent commit?
• ✒️ Is the PR title a valid and meaningful conventional-commit message? ie. type(scope): summary
• 💥 Are breaking changes declared in the PR title in conventional-commit style? ie. type!(scope): summary
• 🎨 Does new code follow the code style of this project?
• 🔍 Has new code been spellchecked and linted?
• 📖 Have docs been updated where necessary?
• 💩 Have commits been checked for accidental file inclusions?

[github-actions]

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