Escaping `%` for parameterized queries
Just use `%%` instead of `%`

When I try to run the trigram Postgres query:
`db.execute_sql("select * from person where person.name % 'bobby'")`

The query crashes with `tuple index out of range` because it thinks the `%` is an argument

I'm wondering if there's a way to escape the `%` sign, so that can put the `%` in the query safely.  If I try to pass it in as an argument to the query, it gets wrapped in a string and the query fails:
`db.execute_sql("select * from person where person.name %s 'foo'", ("%",))`
