Fix python_version

That's what I get for editing after I first woke up on my phone.

setup.py

@@ -44,7 +44,7 @@ def run_tests(self):
     py_modules=['pep8ext_naming'],
     install_requires=['flake8>=5.0.0'],
     zip_safe=False,
-    python_requires='>=3.i',
+    python_requires='>=3.8',
     entry_points={
         'flake8.extension': [
             'N8 = pep8ext_naming:NamingChecker',