hstore_plpython: Fix regression tests under Python 3

contrib/hstore_plpython/expected/hstore_plpython.out

@@ -6,7 +6,7 @@ LANGUAGE plpythonu
 TRANSFORM FOR TYPE hstore
 AS $$
 assert isinstance(val, dict)
-i = val.items()
+i = list(val.items())
 i.sort()
 plpy.info(i)
 return len(val)
@@ -25,7 +25,7 @@ LANGUAGE plpython2u
 TRANSFORM FOR TYPE hstore
 AS $$
 assert isinstance(val, dict)
-i = val.items()
+i = list(val.items())
 i.sort()
 plpy.info(i)
 return len(val)

contrib/hstore_plpython/sql/hstore_plpython.sql

@@ -8,7 +8,7 @@ LANGUAGE plpythonu
 TRANSFORM FOR TYPE hstore
 AS $$
 assert isinstance(val, dict)
-i = val.items()
+i = list(val.items())
 i.sort()
 plpy.info(i)
 return len(val)
@@ -23,7 +23,7 @@ LANGUAGE plpython2u
 TRANSFORM FOR TYPE hstore
 AS $$
 assert isinstance(val, dict)
-i = val.items()
+i = list(val.items())
 i.sort()
 plpy.info(i)
 return len(val)