Adjust expected regression test outputs for PL/python.

This got broken by commit 4c6cedd1b0,
which caused PL/pgsql error messages to print the function
signature, not just the name.

Per buildfarm.

src/pl/plpython/expected/plpython_error.out

@@ -292,7 +292,7 @@ PL/Python function "python_traceback"
 SELECT sql_error();
 ERROR:  division by zero
 CONTEXT:  SQL statement "select 1/0"
-PL/pgSQL function "sql_error" line 3 at SQL statement
+PL/pgSQL function "sql_error()" line 3 at SQL statement
 SELECT python_from_sql_error();
 ERROR:  spiexceptions.DivisionByZero: division by zero
 CONTEXT:  Traceback (most recent call last):
@@ -306,7 +306,7 @@ CONTEXT:  Traceback (most recent call last):
     plpy.execute("select sql_error()")
 PL/Python function "python_traceback"
 SQL statement "select python_traceback()"
-PL/pgSQL function "python_from_sql_error" line 3 at SQL statement
+PL/pgSQL function "python_from_sql_error()" line 3 at SQL statement
 SELECT sql_from_python_error();
 ERROR:  spiexceptions.DivisionByZero: division by zero
 CONTEXT:  Traceback (most recent call last):