[BUG] Fix bug in cast in quantization (#481)

Author: vadiklyutiy

python/hidet/graph/ops/quant/symmetric.py

@@ -11,7 +11,8 @@
 # limitations under the License.
 from typing import Union, List
 from hidet import ir
-from hidet.ir.type import DataType, int32
+from hidet.ir.type import DataType
+from hidet.ir.dtypes import int32
 from hidet.ir.expr import cast, if_then_else
 from hidet.ir.compute.primitives import TensorNode, compute
 from hidet.ir import primitives as prim