message: Add week granularity for Clickhouse
diff: @@ -1350,6 +1350,9 @@ class ClickHouseEngineSpec(BaseEngineSpec):
  Grain('day', _('day'),
  'toStartOfDay(toDateTime({col}))',
  'P1D'),
  + Grain('week', _('week'),
  + 'toMonday(toDateTime({col}))',
  + 'P1W'),
  Grain('month', _('month'),
  'toStartOfMonth(toDateTime({col}))',
  'P1M'),
  