Using typing_extensions for Annotated backport

Author: cswartzvi

tests/test_type_utils.py

@@ -9,6 +9,11 @@
 from hamilton import htypes
 from hamilton.htypes import check_instance
 
+if sys.version_info >= (3, 9):
+    from typing import Annotated
+else:
+    from typing_extensions import Annotated
+
 
 class X:
     pass
@@ -178,7 +183,7 @@ def test__safe_subclass(candidate, type_, expected):
         (pd.Series),
         (htypes.column[pd.Series, int]),
         (pd.DataFrame),
-        (typing.Annotated[int, "metadata"]),
+        (Annotated[int, "metadata"]),
     ],
 )
 def test_get_type_as_string(type_):
@@ -191,7 +196,7 @@ def test_get_type_as_string(type_):
 
 def test_type_as_string_with_annotated_type():
     """Tests the custom_subclass_check"""
-    type_string = htypes.get_type_as_string(typing.Annotated[int, "metadata"])  # type: ignore
+    type_string = htypes.get_type_as_string(Annotated[int, "metadata"])  # type: ignore
     assert type_string == "int"