Style(setup): Fix flake8 F821 undefined name `execfile` under Python 3

diff --git a/setup.py b/setup.py
index c78aa203e86edb644a1025c9114ea742ae6b7ce0..82f1b86ae47f3614920e283b0d61d171ed95cd19 100755 (executable)
--- a/setup.py
+++ b/setup.py
@@ -8,7 +8,7 @@ versionpath = join(abspath(dirname(__file__)), 'm_librarian', '__version__.py')
 m_librarian_version = {}
 
 if sys.version_info[:2] == (2, 7):
-    execfile(versionpath, m_librarian_version)
+    execfile(versionpath, m_librarian_version)  # noqa: F821 'execfile' Py3
 
 elif sys.version_info >= (3, 4):
     exec(open(versionpath, 'rU').read(), m_librarian_version)