refactor: update substrait.gen.antlr imports

Author: vbarua

src/substrait/derivation_expression.py

@@ -2,9 +2,8 @@
 
 from antlr4 import CommonTokenStream, InputStream
 from substrait.type_pb2 import NamedStruct, Type
-
-from substrait.gen.antlr.SubstraitTypeLexer import SubstraitTypeLexer
-from substrait.gen.antlr.SubstraitTypeParser import SubstraitTypeParser
+from substrait_antlr.substrait_type.SubstraitTypeLexer import SubstraitTypeLexer
+from substrait_antlr.substrait_type.SubstraitTypeParser import SubstraitTypeParser
 
 
 def _evaluate(x, values: dict):

src/substrait/extension_registry/signature_checker_helpers.py

@@ -3,9 +3,9 @@
 from typing import Dict
 
 from substrait.type_pb2 import Type
+from substrait_antlr.substrait_type.SubstraitTypeParser import SubstraitTypeParser
 
 from substrait.derivation_expression import _evaluate
-from substrait.gen.antlr.SubstraitTypeParser import SubstraitTypeParser
 
 from .exceptions import UnhandledParameterizedTypeError, UnrecognizedSubstraitTypeError