Update setup.py
diff --git a/setup.py b/setup.py
index a8bc4ff..31ecca0 100755
--- a/setup.py
+++ b/setup.py
@@ -64,6 +64,7 @@
         scripts=['tools/sl4a_shell.py', 'tools/snippet_shell.py'],
         tests_require=[
             'mock',
+            # Needed for supporting Python 2 because this release stopped supporting Python 2.
             'pytest<5.0.0',
             'pytz',
         ],