added tests for all formatters; stylecheck workflow now also checks in tests now

tests/tests_converter.py

@@ -6,7 +6,7 @@ from html_to_django import converter
 
 
 class ConverterTests(TestCase):
-    def test_convert_file(self):
+    def test_convert_file(self) -> None:
         shutil.copytree(
             os.path.abspath("tests/test_project"),
             os.path.abspath("tests/test_project_test_result"),