Update the Python package classifiers to reflect the correct Python compatibility.

PiperOrigin-RevId: 343404565

tensorflow_federated/tools/development/setup.py

@@ -123,6 +123,7 @@ setuptools.setup(
         'Programming Language :: Python :: 3',
         'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',
+        'Programming Language :: Python :: 3.8',
         'Topic :: Scientific/Engineering',
         'Topic :: Scientific/Engineering :: Mathematics',
         'Topic :: Scientific/Engineering :: Artificial Intelligence',