chore(deps): Bump hyperledger/aries-cloudagent-python from py3.9-0.12.2 to py3.9-0.12.3 in /demo/multi-demo

chore(deps): Bump hyperledger/aries-cloudagent-python from py3.9-0.12.2 to py3.9-0.12.3 in /demo/multi-demo #834