Add python versions

Author: luozhouyang

setup.py

@@ -18,6 +18,10 @@
     license="MIT License",
     classifiers=(
         "Programming Language :: Python :: 3",
+        "Programming Language :: Python :: 3.5",
+        "Programming Language :: Python :: 3.6",
+        "Programming Language :: Python :: 3.7",
+        "Programming Language :: Python :: 3.8",
         "License :: OSI Approved :: MIT License",
         "Operating System :: OS Independent",
     )