[docs] improve UPDATING.md around 0.31's [now] optional deps (#7117)
[docs] improve UPDATING.md around 0.31's [now] optional deps (#7117)


airbnb/caravel,airbnb/superset,mistercrunch/panoramix,airbnb/caravel,zhouyao1994/incubator-superset,airbnb/superset,zhouyao1994/incubator-superset,mistercrunch/panoramix,zhouyao1994/incubator-superset,airbnb/caravel,apache/incubator-superset,mistercrunch/panoramix,airbnb/caravel,apache/incubator-superset,airbnb/superset,apache/incubator-superset,zhouyao1994/incubator-superset,apache/incubator-superset,mistercrunch/panoramix,zhouyao1994/incubator-superset,airbnb/superset,apache/incubator-superset