trove classifiers should be a list, not a tuple

setup.py

@@ -38,12 +38,12 @@ setup(
     url='https://github.com/atdt/monotonic',
     description='An implementation of time.monotonic() for Python 2 & < 3.3',
     long_description=__doc__,
-    classifiers=(
+    classifiers=[
         'Development Status :: 5 - Production/Stable',
         'License :: OSI Approved :: Apache Software License',
         'Programming Language :: Python :: 2',
         'Programming Language :: Python :: 3',
         'Topic :: Software Development :: Libraries :: Python Modules',
-    ),
+    ],
     py_modules=('monotonic',),
 )