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

chore(deps): Bump hyperledger/aries-cloudagent-python from py3.9-0.12.2 to py3.9-0.12.3 in /demo/playground #835