Replace newer type hint syntax with older syntax supported by Python 3.9

refscan/lib/ReferenceList.py

@@ -1,4 +1,4 @@
-from typing import List, Dict
+from typing import List, Dict, Union
 from pathlib import Path
 from dataclasses import fields, astuple
 from collections import UserList
@@ -88,7 +88,7 @@ def make_group_key(reference: Reference) -> tuple:
         groups = groupby(sorted(self.data), key=make_group_key)
         return groups
 
-    def dump_to_tsv_file(self, file_path: str | Path) -> None:
+    def dump_to_tsv_file(self, file_path: Union[str, Path]) -> None:
         r"""
         Helper function that dumps the references to a TSV file at the specified path.
         """

refscan/lib/ViolationList.py

@@ -1,3 +1,4 @@
+from typing import Union
 from pathlib import Path
 from dataclasses import fields, astuple
 from collections import UserList
@@ -12,7 +13,7 @@ class ViolationList(UserList):
     """
 
     def dump_to_tsv_file(
-        self, file_path: str | Path, include_name_of_collection_containing_target: bool = True
+        self, file_path: Union[str, Path], include_name_of_collection_containing_target: bool = True
     ) -> None:
         """
         Helper function that dumps the violations to a TSV file at the specified path.

refscan/refgraph.py

@@ -1,6 +1,6 @@
 from enum import Enum
 from pathlib import Path
-from typing import Optional
+from typing import Optional, Union
 from typing_extensions import Annotated
 import json
 import base64
@@ -47,7 +47,7 @@ def load_template(resource_path: str) -> str:
     return resources.files(package_name).joinpath(resource_path).read_text(encoding="utf-8")
 
 
-def encode_json_value_as_base64_str(json_value: dict | list) -> str:
+def encode_json_value_as_base64_str(json_value: Union[dict, list]) -> str:
     r"""Helper function that encodes the specified JSON value as a base64 string."""
 
     value_as_string = json.dumps(json_value)