Fixing volume for unstable_cluster docker (#1914)

(cherry picked from commit 8499adc)

Author: dvora-h

tox.ini

@@ -53,7 +53,7 @@ ports =
     6377:6377/tcp
 healtcheck_cmd = python -c "import socket;print(True) if all([0 == socket.socket(socket.AF_INET, socket.SOCK_STREAM).connect_ex(('127.0.0.1',port)) for port in range(6372,6377)]) else False"
 volumes =
-    bind:rw:{toxinidir}/docker/cluster/redis.conf:/redis.conf
+    bind:rw:{toxinidir}/docker/unstable_cluster/redis.conf:/redis.conf
 
 [docker:sentinel_1]
 name = sentinel_1