To create valid Snap HTTP request, merchant have to add 3 headers:
Accept: application/json
Content-Type: application/json
Authorization: Basic AUTH_STRING
SERVER_KEY = "VT-server-Cpo03kYDOc0cNUKgt6hnLkKg"
AUTH_STRING = Base64("VT-server-Cpo03kYDOc0cNUKgt6hnLkKg:")
AUTH_STRING = "VlQtc2VydmVyLUNwbzAza1lET2MwY05VS2d0NmhuTGtLZzo="