Add query_error_to_string

[sporto]

I would like to have a quick way to convert the query errors to a string

fn find_user(email: String) ->  Result(User, String) {
  ...

  use returned <- result.try(
    pgo.execute(select_sql, db, [pgo.text(email)], return_type)
    |> result.map_error(pgo.query_error_to_string),
  )

  ...
}

What do you think?
Would be nice if dynamic could have this too