Fixed variable name

Author: wiazur

samples/vision/content_moderator_image_review.py

@@ -81,4 +81,4 @@ def image_review(subscription_key):
     import os.path
     sys.path.append(os.path.abspath(os.path.join(__file__, "..", "..")))
     from samples.tools import execute_samples
-    execute_samples(globals(), SUBSCRIPTION_KEY_ENV_NAME)
+    execute_samples(globals(), SUBSCRIPTION_KEY)