MAINT: missed python descs [skip ci]

Author: mgxd

.travis.yml

@@ -6,7 +6,7 @@ cache:
     - $HOME/.cache/pip
 
 python:
-  - 3.6
+  - 3.7
 
 before_install:
   - python -m pip install --upgrade pip

setup.cfg

@@ -13,12 +13,11 @@ classifiers =
     Intended Audience :: Science/Research
     Topic :: Scientific/Engineering :: Image Recognition
     License :: OSI Approved :: BSD License
-    Programming Language :: Python :: 3.5
-    Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
+    Programming Language :: Python :: 3.8
 
 [options]
-python_requires = >=3.5
+python_requires = >=3.7
 install_requires =
     indexed_gzip >= 0.8.8
     nibabel >= 3.0.1