make sure to close files

setup.py

@@ -5,10 +5,16 @@
 import sys
 from setuptools import setup
 
-README = open(os.path.join(os.path.dirname(__file__), "README.rst")).read()
-CONTRIB = open(os.path.join(os.path.dirname(__file__), "CONTRIBUTING.rst")).read()
-CHANGES = open(os.path.join(os.path.dirname(__file__), "CHANGES.rst")).read()
-version = open(os.path.join(os.path.dirname(__file__), "VERSION.txt")).read().strip()
+
+def read_file(fname):
+    with open(os.path.join(os.path.dirname(__file__), fname)) as r:
+        return r.read()
+
+
+README = read_file("README.rst")
+CONTRIB = read_file("CONTRIBUTING.rst")
+CHANGES = read_file("CHANGES.rst")
+version = read_file("VERSION.txt").strip()
 
 needs_pytest = {'pytest', 'test', 'ptr'}.intersection(sys.argv)
 pytest_runner = ['pytest-runner'] if needs_pytest else []
@@ -32,7 +38,7 @@
     packages=["luma.oled"],
     zip_safe=False,
     install_requires=["luma.core>=0.2.0"],
-    setup_requires=[] + pytest_runner,
+    setup_requires=pytest_runner,
     tests_require=["mock", "pytest", "pytest-cov", "python-coveralls"],
     classifiers=[
         "License :: OSI Approved :: MIT License",