Bounty Cleanup Proposal

I'm suggesting a cleanup of several bounties on Polkadot as part of our ongoing housekeeping efforts to ensure a well-maintained and efficient chain environment.

The identified list comprises 10 bounties (13, 18, 20, 21, 23, 25, 26, 29, 34, 35). The decision to close these bounties is grounded in specific reasons:

1. Inactive/Outdated: These bounties lack ongoing relevance or activity.
2. Lack of Contextual Information: Bounties without sufficient contextual details are marked for closure.
3. Expired Curators: In instances where the curator's expiration date has lapsed without an extension and as a result the curator has already been removed.

Please note that the action of closing the previously funded bounty would return any remnant funds on the bounty account to the treasury and remove the curator (if assigned).