/material/get_material 获取图文素材，返回的thumb_media_id不稳定,同一篇文章有时候能取到，有时候取不到

https://api.weixin.qq.com/cgi-bin/material/get_material?access_token=46_i3j5KemsKP_csl5Vec9Kc8bgURkgTsYbPZC2Ajs4fioCXC8mKADErDnCAXSAGpSGscz-seOWgS4wRoIGfyD3sdJ8hsSC5u24_ghpaArjVAl34hki_quTdqfEd-VdVx6Dc421vzOe_jLegf3dVILfAFDGTW

{

"media_id":"pG52DT-cB80824ubQB_65IWDC9b63jV05WLBiX04NPE"

}