message: Fix monthly time grain in sqllite
diff: @@ -193,7 +193,7 @@ class SqliteEngineSpec(BaseEngineSpec):
  Grain("week", _('week'),
  "DATE({col}, -strftime('%w', {col}) || ' days')"),
  Grain("month", _('month'),
  - "DATE({col}, -strftime('%d', {col}) || ' days')"),
  + "DATE({col}, -strftime('%d', {col}) || ' days', '+1 day')"),
  )
  @classmethod
  