test(test_subsampling): fix dictionary access

Author: nialov

tests/analysis/test_subsampling.py

@@ -25,7 +25,7 @@ def test_aggregate_chosen(
     for value in result.values():
         assert isinstance(value, value_type)
 
-    for col, assumed_result_value in assumed_results:
+    for col, assumed_result_value in assumed_results.items():
         assert col in result
         result_value = result[col]
         if isinstance(result_value, str):