Update Clickhouse

Src/Asp.NetCore2/SqlSugar.ClickHouseCore/ClickHouse/DbMaintenance/ClickHouseDbMaintenance.cs

@@ -23,7 +23,7 @@ namespace SqlSugar.ClickHouse
                 string schema = GetSchema();
                 string sql = @"select table_name  as TableName,
  column_type as  DataType ,
- is_nullable  as IsNullable,
+ cast(is_nullable as bool)  as IsNullable,
  column_name DbColumnName,
  column_comment as  ColumnDescription  from information_schema.columns a  where lower(table_name) =lower('{0}') and lower(table_schema) = lower('"+schema+"')";
                 return sql;