Allow content payload exceeds 1MB

[zhang699]

since Get repository content would use base64-encoded when size less than 1MB, but when the size exceed 1MB, the encoded payload became empty ''

{
  content: ""
  download_url: "https://raw.githubusercontent.com/zhang699/translations/b11706c2aff98a97988faf9d38a873565053d4c7/xxx.json?token=ABIL4IH7KXMQWJ2IS5LK7TTC4O3FG"
  encoding: "none"
}

one of solution I think we can use download_url to fetch the raw