[landing][web] Update to ethers@5.7.2

Summary: keyserver had a newer version for some reason.

Test Plan: We're only updating from 5.7.0 to 5.7.2. Confirmed in release notes that should be no breaking changes

Reviewers: atul

Reviewed By: atul

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D6263