stack, err := auto.UpsertStackInlineSource(context.Background(), stackName, projectName, pulumiMain, opts...)
    if err != nil {
        fmt.Printf("Error in UpsertStackInlineSource: %v\n", err)
        panic(err)
    }

    stack.SetConfig(context.Background(), "aws:assumeRole", auto.ConfigValue{
        Value: `{
            "roleArn": "arn:aws:iam::123456789:role/testDeployRole",
            "sessionName": "mySessionName"
        }`,
    })