Update setup.py for Python 3.6+ requirement

Author: oschwald

setup.py

@@ -24,9 +24,8 @@
     package_data={"": ["LICENSE"]},
     package_dir={"geoip2": "geoip2"},
     include_package_data=True,
-    python_requires=">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*",
+    python_requires=">=3.6",
     install_requires=requirements,
-    extras_require={':python_version=="2.7"': ["ipaddress"]},
     tests_require=["requests_mock>=0.5"],
     test_suite="tests",
     license=geoip2.__license__,
@@ -36,9 +35,7 @@
         "Intended Audience :: Developers",
         "Intended Audience :: System Administrators",
         "License :: OSI Approved :: Apache Software License",
-        "Programming Language :: Python :: 2.7",
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.5",
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",