Support for PoolFIFO option

[siriele]

redis v9 introduced a PoolFifo option that ths library does not pass on.

	// PoolFIFO type of connection pool.
	//
	//	- true for FIFO pool
	//	- false for LIFO pool.
	//
	// Note that FIFO has slightly higher overhead compared to LIFO,
	// but it helps closing idle connections faster reducing the pool size.
	PoolFIFO bool