Conform to 3.9 union type formatting

Signed-off-by: Will Beason <willbeason@gmail.com>

test/Wikiq_Unit_Test.py

@@ -11,7 +11,7 @@ from pandas import DataFrame
 from pandas.testing import assert_frame_equal, assert_series_equal
 from io import StringIO
 import tracemalloc
-from typing import Final
+from typing import Final, Union
 
 # Make references to files and wikiq relative to this file, not to the current working directory.
 TEST_DIR: Final[str] = os.path.dirname(os.path.realpath(__file__))
@@ -42,7 +42,7 @@ class WikiqTester:
     def __init__(self,
                  wiki: str,
                  case_name: str,
-                 suffix: str | None = None,
+                 suffix: Union[str, None] = None,
                  in_compression: str = "bz2",
                  baseline_format: str = "tsv",
                  out_format: str = "tsv",