🧎‍♀️ Genuflect to the types.

Add a redundant type definition to a test to avoid warnings about the inner types being unchecked. Closes #478.

tests/test_main.py

@@ -400,7 +400,7 @@ def test_packages_distributions_all_module_types(self):
 
         assert not any(name.endswith('.dist-info') for name in distributions)
 
-    def test_packages_distributions_symlinked_top_level(self):
+    def test_packages_distributions_symlinked_top_level(self) -> None:
         """
         Distribution is resolvable from a simple top-level symlink in RECORD.
         See #452.