We should auto-close stray PRs

[soc-pe-bot]

as per title

[nus-pe-script]

I agree

[soc-se-script]

yes we should. I agree

[soc-se-bot-red]

yes we should. I agree

But do we need to give a grace period

[damithc]

Too much automation may not be a good thing though 🤔