Summary

This is a full release that upgrades Substrate / Cumulus / Polkadot version to v0.9.16 to be compatible with the new release of the relaychain.

Release Note: https://github.com/AcalaNetwork/Acala/releases/tag/2.3.1

Referendum

• https://karura.subscan.io/referenda/37
• https://karura.subsquare.io/democracy/referendum/37