Update supported Python version for kubeflow-katib SDK (#1797)

* update supported Python version for kubeflow-katib SDK

* stop supporting Python2

Author: tenzen-y

sdk/python/v1beta1/setup.py

@@ -35,11 +35,12 @@
         'Intended Audience :: Developers',
         'Intended Audience :: Education',
         'Intended Audience :: Science/Research',
-        'Programming Language :: Python :: 2',
-        'Programming Language :: Python :: 2.7',
         'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3 :: Only',
         'Programming Language :: Python :: 3.7',
+        'Programming Language :: Python :: 3.8',
+        'Programming Language :: Python :: 3.9',
+        'Programming Language :: Python :: 3.10',
         "License :: OSI Approved :: Apache Software License",
         "Operating System :: OS Independent",
         'Topic :: Scientific/Engineering',