Add a stale issue GH action

[jayjb]

Proposed changes

This commit introduces an automated checker for stale issues and PRs. We are going to start basic with this one and we can build onto it if more functionality is required.

Types of changes

What types of changes does your code introduce to this repository?
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• New feature (non-breaking change which adds functionality)

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• Lint and unit tests pass locally with my changes (if applicable)
• I have run pre-commit (pre-commit in the repo)