Use Union instead of |

Author: JamesParrott

src/shapefile.py

@@ -2102,7 +2102,9 @@ def __getitem__(
         :return: the value of the field
         """
         try:
-            return list.__getitem__(self, cast(SupportsIndex | slice, item))
+            # Using | on types in Python 3.9 also raises TypeError, so Union needed.
+            # as we subsequently catch TypeError
+            return list.__getitem__(self, cast(Union[SupportsIndex, slice], item))
         except TypeError:
             try:
                 index = self.__field_positions[cast(str, item)]
@@ -2132,9 +2134,11 @@ def __setitem__(
         :param key: Either the position of the value or the name of a field
         :param value: the new value of the field
         """
-        ValidKVTuple = (
-            tuple[SupportsIndex, RecordValue] | tuple[slice, Iterable[RecordValue]]
-        )
+        # Using | on types in Python 3.9 also raises TypeError, so Union needed.
+        # as we subsequently catch TypeError
+        ValidKVTuple = Union[
+            tuple[SupportsIndex, RecordValue], tuple[slice, Iterable[RecordValue]]
+        ]
         try:
             list.__setitem__(self, *cast(ValidKVTuple, (key, value)))
             return