Update apollo-cache-inmemory to 1.6.3 version

Summary

!19236 (merged) upgraded apollo library to version 2.6 and updated our config with immutability by default. Unfortunately, since apollo-cache-inmemory was not upgraded, freezeResults config has no actual effect. This results in poor developer experience and does not effectively catch our mutations during development (see gitlab-org/frontend/rfcs#34 (closed) for example)

Solution

Upgrade apollo-cache-inmemory to 1.6.3, so freezeResults have actual effect

/cc @iamphill because of !19236 (merged)