Bump python version

Bump tests version and supported versions in setup.py

stdlib: update packages for python 3.9

By utilizing the packages listed in
https://github.com/jackmaney/python-stdlib-list
for python 3.8 and 3.9, we were able to drop all stdlib packages that
existed solely in python 2 and add the missing stdlib python 3 packages

.travis.yml

@@ -4,17 +4,17 @@ language: python
 
 matrix:
   include:
+    - python: 3.9
+      env: TOX_ENV=py39
+    - python: 3.8
+      env: TOX_ENV=py38
+    - python: 3.7
+      env: TOX_ENV=py37
     - python: 3.6
       env: TOX_ENV=py36
-    - python: 3.5
-      env: TOX_ENV=py35
-    - python: 3.4
-      env: TOX_ENV=py34
-    - python: 2.7
-      env: TOX_ENV=py27
     - python: pypy3
       env: TOX_ENV=pypy3
-    - python: 3.6
+    - python: 3.9
       env: TOX_ENV=flake8
 
 # Use tox to run tests on Travis-CI to keep one unified method of running tests in any environment

setup.py

@@ -1,6 +1,4 @@
 #!/usr/bin/env python
-# -*- coding: utf-8 -*-
-
 
 try:
     from setuptools import setup
@@ -34,7 +32,7 @@ setup(
     package_dir={'pipreqs':
                  'pipreqs'},
     include_package_data=True,
-    package_data={'': ['stdlib','mapping']},
+    package_data={'': ['stdlib', 'mapping']},
     install_requires=requirements,
     license='Apache License',
     zip_safe=False,
@@ -44,12 +42,11 @@ setup(
         'Intended Audience :: Developers',
         'License :: OSI Approved :: Apache Software License',
         'Natural Language :: English',
-        'Programming Language :: Python :: 2',
-        'Programming Language :: Python :: 2.7',
         'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.4',
-        'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
+        'Programming Language :: Python :: 3.8',
+        'Programming Language :: Python :: 3.9',
     ],
     test_suite='tests',
     entry_points={

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py27, py34, py35, py36, pypy3, flake8
+envlist = py36, py37, py38, py39, pypy3, flake8
 
 [testenv]
 setenv =
@@ -9,7 +9,7 @@ deps =
     -r{toxinidir}/requirements.txt
 
 [testenv:flake8]
-basepython = python3.6
+basepython = python3.9
 commands = flake8 pipreqs
 deps =
     -r{toxinidir}/requirements.txt