Withdraw 18,000 USDC to Escrow

Per the discussion outlined here: https://gdao.network/t/proposal-discussion-18-000-usdc-to-escrow-for-amicable-departure/2720

Withdraw 18,000 USDC from Aragon treasury to escrow for Uni's amicable departure.

Vote runs for 72 hours and requires majority approval to pass. At that time, treasury signers will execute a withdrawal from Aragon for the aforementioned sum of USDC.