Fixed a typo.

Author: xordoquy

setup.py

@@ -48,7 +48,7 @@ def get_package_data(package):
     if os.system("pip freeze | grep wheel"):
         print("wheel not installed.\nUse `pip install wheel`.\nExiting.")
         sys.exit()
-    if os.system("pip freeze | grep twine")
+    if os.system("pip freeze | grep twine"):
         print("twine not installed.\nUse `pip install twine`.\nExiting.")
         sys.exit()
     os.system("python setup.py sdist bdist_wheel")