Translations API: fix #build_project_file_translation when the eTag param is passed

[artem-vavilov]

Issue

The method #build_project_file_translation sends eTag as a request parameter.

{
  "errors": [
    {
      "error": {
        "key": "eTag",
        "errors": [
          {
            "code": "notFound",
            "message": "Field 'eTag' Not Found"
          }
        ]
      }
    }
  ]
}