Can't parse jsonb extractions in an on conflict in Postgres

The parser does not support the following:

```sql
INSERT INTO table_with_constraint_over_jsonb (a_number, a_jsonb, a_string) 
VALUES ($1, $2, $3) 
ON CONFLICT (a_number, (a_jsonb->>'name')) 
DO UPDATE SET a_string = EXCLUDED.a_string 
RETURNING *;
```

It errors on the `(a_jsonb->>'name')` part with the error: `ParserError("Expected: identifier, found: ( at Line: 1, Column: 119")`.