PL/Python: Adjust the regression tests for Python 3.3

Similar to 2cfb1c6f77, the order in which
dictionary elements are printed is not reliable.  This reappeared in the
tests of the string representation of result objects.  Reduce the test
case to one result set column so that there is no question of order.

src/pl/plpython/expected/plpython_spi.out

@@ -269,10 +269,10 @@ plan = plpy.prepare(cmd)
 result = plpy.execute(plan)
 return str(result)
 $$ LANGUAGE plpythonu;
-SELECT result_str_test($$SELECT 1 AS foo, '11'::text AS bar UNION SELECT 2, '22'$$);
+SELECT result_str_test($$SELECT 1 AS foo UNION SELECT 2$$);
                       result_str_test                       
---------------------------------------------------------------------------------------
- <PLyResult status=5 nrows=2 rows=[{'foo': 1, 'bar': '11'}, {'foo': 2, 'bar': '22'}]>
+------------------------------------------------------------
+ <PLyResult status=5 nrows=2 rows=[{'foo': 1}, {'foo': 2}]>
 (1 row)
 
 SELECT result_str_test($$CREATE TEMPORARY TABLE foo1 (a int, b text)$$);

src/pl/plpython/sql/plpython_spi.sql

@@ -176,7 +176,7 @@ result = plpy.execute(plan)
 return str(result)
 $$ LANGUAGE plpythonu;
 
-SELECT result_str_test($$SELECT 1 AS foo, '11'::text AS bar UNION SELECT 2, '22'$$);
+SELECT result_str_test($$SELECT 1 AS foo UNION SELECT 2$$);
 SELECT result_str_test($$CREATE TEMPORARY TABLE foo1 (a int, b text)$$);
 
 -- cursor objects