use redis 8.2.1 in testing

Author: ppapapetrou76

.github/configs/external-redis.yaml

@@ -29,7 +29,7 @@ spec:
         - --appendonly
         - "no"
         - --requirepass argocd
-        image: ecr-public.aws.com/docker/library/redis:7.2.8-alpine
+        image: ecr-public.aws.com/docker/library/redis:8.2.1-alpine
         name: redis
         ports:
         - containerPort: 6379