Making noxfile <3.9 compatible

noxfile.py

@@ -16,7 +16,7 @@
 import string
 import subprocess
 from glob import glob
-from typing import List, Tuple
+from typing import List, Set, Tuple
 
 import nox
 
@@ -604,7 +604,7 @@ def make_release_commit(session):
 
 
 def load_allowed_change_types(project_toml: pathlib.Path = pathlib.Path('./pyproject.toml')
-                             ) -> set[str]:
+                             ) -> Set[str]:
     """
     Load the list of allowed change types from the pyproject.toml file.
     """
@@ -613,7 +613,7 @@ def load_allowed_change_types(project_toml: pathlib.Path = pathlib.Path('./pypro
     return set(entry['directory'] for entry in configuration['tool']['towncrier']['type'])
 
 
-def is_changelog_filename_valid(filename: str, allowed_change_types: set[str]) -> tuple[bool, str]:
+def is_changelog_filename_valid(filename: str, allowed_change_types: Set[str]) -> Tuple[bool, str]:
     """
     Validates whether the given filename matches our rules.
     Provides information about why it doesn't match them.
@@ -647,7 +647,7 @@ def is_changelog_filename_valid(filename: str, allowed_change_types: set[str]) -
     return len(error_reasons) == 0, ' / '.join(error_reasons) if error_reasons else ''
 
 
-def is_changelog_entry_valid(file_content: str) -> tuple[bool, str]:
+def is_changelog_entry_valid(file_content: str) -> Tuple[bool, str]:
     """
     We expect the changelog entry to be a valid sentence in the English language.
     This includes, but not limits to, providing a capital letter at the start