Security advisory DB: allow editing PRs while they are awaiting review

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I made a pull request to the GHSA DB today, and when I did, it seems that the editor deleted one of the references. I'm 100% sure that I didn't do this myself (pretty sure this is some kind of advisory editor bug), but now I cannot modify the PR since the edit button is grayed out. It would be amazing if you could edit these PRs after creating them, and would greatly improve the process of contributing to the advisory database.