Update Redis slave image

The old image required the `vsyscall=emulate` kernel parameter to work
correctly because of an old glibc version which is incompatible with
newer kernels.

This fails with Rancher Desktop for example.

Details at: https://github.com/rancher-sandbox/rancher-desktop/issues/2215

simple/redis-slave-deployment.yaml

@@ -18,7 +18,7 @@ spec:
     spec:
       containers:
       - name: slave
-        image: gcr.io/google_samples/gb-redisslave:v1
+        image: gcr.io/google_samples/gb-redisslave:v2
         resources:
           requests:
             cpu: 100m