await when calling SequenceWallet.DeployContract from within an async Task if you wish to obtain the ContractDeploymentReturn object directly. Or, you can take the recommended approach which is to setup handler functions for the SequenceWallet.OnDeployContractComplete and SequenceWallet.OnDeployContractFailed events and call the SequenceWallet.DeployContract method from anywhere (without await).
SequenceWallet.DeployContract is essentially a wrapper for a very special SequenceWallet.SendTransaction call and therefore, you can expect to still receive the SequenceWallet.OnSendTransactionComplete or SequenceWallet.OnSendTransactionFailed events in addition.