fix pipeline for older python

Author: Ran Isenberg

aws_lambda_powertools/utilities/parser/models/custom_resource.py

@@ -1,7 +1,9 @@
-from typing import Any, Dict, Literal, Type, Union
+from typing import Any, Dict, Type, Union
 
 from pydantic import BaseModel, Field, HttpUrl
 
+from aws_lambda_powertools.utilities.parser.types import Literal
+
 
 class CustomResourceBaseModel(BaseModel):
     request_type: str = Field(..., alias="RequestType")