Reference of v2 update

Fetch latest release and offer a direct download url.

Return data

{
    "status": 0,
    "content": {
        "url": "https://static-lb.lowiro.com/serve/arcaea_3.4.2c.apk?token=uXnTMlGm94bJ3sCPH4aSZmpx5SXZnr2vzeKMB6ySun693Gox8ovicfDDZsUw56jRr",
        "version": "3.4.2c"
    }
}

Error status

status	description
0	everything is OK
-1	service unavailable
-2	fetch latest release failed
-233	unknown error occurred