All Mac builders in both framework and devicelab need to use xcode 12.3 which includes swift #73623
Description
Most of Mac builders are using an old xcode version 11.3, which misses swift dependency. This causes intermittent problems like:
#73606
#72823
Per discussions https://github.com/flutter/infra/pull/325, we need update all builders to use latest xcode 12.3.