Seems like you have posted same on GitHub. How to download a file attachment with golang sdk
Currently, as a workaround yes you can use below code and use another request builder that performs a similar function to download a file attachment with Golang:
rawUrl := "https://graph.microsoft.com/v1.0/users/{user-id}/messages/{message-id}/attachments/{attachment-id}/$value"
builder := users.NewItemPhotoValueContentRequestBuilder(rawUrl, requestAdapter)
attachmentValue, err := builder.Get(context.Background(), nil)
Hope this helps.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".