/// Returns a borrow rate multiplier according to the provided utilization of a market. The returned value will be equal to:
/// * 0.25 at utilization 0%
/// * 1.0 at utilization 90%
/// * 4.0 at utilization 100%
/// # Parameters
/// - `utilization` Current utilization (1.0 is equal to 100%)
/// # Returns
/// Borrow rate multiplier.