deprecate support for 3.6

Author: jschlyter

setup.py

@@ -47,9 +47,9 @@
         "Development Status :: 4 - Beta",
         "License :: OSI Approved :: Apache Software License",
         "Topic :: Software Development :: Libraries :: Python Modules",
-        "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
     ],
     install_requires=["cryptography", "requests"],
     tests_require=["pytest"],