use wagmi erc20 import in useTokenBalances.tsx

[wildmolasses]

(nit)

We couldn't get the types to line up in #32. let's see if we can use this import by making small type adjustments.

per @mds1 we can use a wagmi import here:

import { erc20ABI } from "@wagmi/core";

Originally posted by @wildmolasses in #32 (comment)