package/redis: security bump to 6.0.8

package/redis: security bump to 6.0.8

>From the release notes
See: https://github.com/redis/redis/blob/6.0.8/00-RELEASENOTES

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Redis 6.0.7     Released Fri Aug 28 11:05:09 IDT 2020
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Upgrade urgency MODERATE: several bugs with moderate impact are fixed,
Specifically the first two listed below which cause protocol errors for clients.

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Redis 6.0.8     Released Wed Sep 09 23:34:17 IDT 2020
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Upgrade urgency HIGH: Anyone who's using Redis 6.0.7 with Sentinel or
CONFIG REWRITE command is affected and should upgrade ASAP, see #7760.

Signed-off-by: Titouan Christophe <titouan.christophe@railnova.eu>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>