Release notes

• Outdated ETH testnet networks (Rinkeby, Goerli, etc) information has been removed.
• Geth dependency upgraded to from 1.13.11 to 1.13.14.
• Shutdown gRPC server when GW is not synced (same as for WS).
• Prevent GW to process the same block multiple times on Beacon API.
• Log error when GW has no connected peers to broadcast Beacon block.