fix tests for python 3.x

moto/awslambda/models.py

@@ -111,7 +111,7 @@ class LambdaFunction(BaseModel):
         }
 
     def get_code(self):
-        if 'S3Key' in self.code:
+        if isinstance(self.code, dict):
             return {
                 "Code": {
                     "Location": "s3://lambda-functions.aws.amazon.com/{0}".format(self.code['S3Key']),

tests/test_awslambda/test_lambda.py

@@ -624,4 +624,4 @@ def test_get_function_created_with_zipfile():
                 "SubnetIds": [],
             }
         },
-    )
+    )