Fix deployment check return value

AssertionError: The function <function storage_check at 0x7f8571c1a048> did not return a list. All functions registered with the checks registry must return a list.

Author: codingjoe

s3file/checks.py

@@ -11,3 +11,4 @@ def storage_check(app_configs, **kwargs):
                 id='s3file.E001',
             )
         ]
+    return []