MAINT: Set minimum versions

Set minimum to Pthon 3.6

Author: bashtage

setup.cfg

@@ -1,6 +1,3 @@
-[bdist_wheel]
-universal = 1
-
 [versioneer]
 VCS = git
 style = pep440

setup.py

@@ -36,12 +36,10 @@ def readme():
         "Intended Audience :: Science/Research",
         "Operating System :: OS Independent",
         "Programming Language :: Python",
-        "Programming Language :: Python :: 2",
-        "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",
         "Topic :: Scientific/Engineering",
     ],
     keywords="data",
@@ -50,5 +48,5 @@ def readme():
     test_suite="tests",
     tests_require=tests_require,
     zip_safe=False,
-    python_requires=">=3.5",
+    python_requires=">=3.6",
 )