Fix quotes in setup.py

setup.py

@@ -10,32 +10,32 @@ try:
 finally:
     version_file.close()
 
-exec(compile(version_file_contents, "pytools/version.py", 'exec'), ver_dic)
+exec(compile(version_file_contents, "pytools/version.py", "exec"), ver_dic)
 
 setup(name="pytools",
       version=ver_dic["VERSION_TEXT"],
       description="A collection of tools for Python",
       long_description=open("README.rst", "r").read(),
       classifiers=[
-          'Development Status :: 4 - Beta',
-          'Intended Audience :: Developers',
-          'Intended Audience :: Other Audience',
-          'Intended Audience :: Science/Research',
-          'License :: OSI Approved :: MIT License',
-          'Natural Language :: English',
-          'Programming Language :: Python',
-          'Programming Language :: Python :: 3',
-          'Programming Language :: Python :: 3.6',
-          'Programming Language :: Python :: 3.7',
-          'Topic :: Scientific/Engineering',
-          'Topic :: Scientific/Engineering :: Information Analysis',
-          'Topic :: Scientific/Engineering :: Mathematics',
-          'Topic :: Scientific/Engineering :: Visualization',
-          'Topic :: Software Development :: Libraries',
-          'Topic :: Utilities',
+          "Development Status :: 4 - Beta",
+          "Intended Audience :: Developers",
+          "Intended Audience :: Other Audience",
+          "Intended Audience :: Science/Research",
+          "License :: OSI Approved :: MIT License",
+          "Natural Language :: English",
+          "Programming Language :: Python",
+          "Programming Language :: Python :: 3",
+          "Programming Language :: Python :: 3.6",
+          "Programming Language :: Python :: 3.7",
+          "Topic :: Scientific/Engineering",
+          "Topic :: Scientific/Engineering :: Information Analysis",
+          "Topic :: Scientific/Engineering :: Mathematics",
+          "Topic :: Scientific/Engineering :: Visualization",
+          "Topic :: Software Development :: Libraries",
+          "Topic :: Utilities",
           ],
 
-      python_requires='~=3.6',
+      python_requires="~=3.6",
 
       install_requires=[
           "decorator>=3.2.0",