vm_setup.sh: add iptables dependency

We started to use iptables in patch 21bd94275
(libsock: add functional tests) but never added
the package dependency.

Change-Id: I651f2545a11f546f8b47f9759fbaed3a141f0928
Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/c/443597 (master)
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/447590
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>

test/common/config/vm_setup.sh

@@ -426,7 +426,8 @@ if $INSTALL; then
     sshfs \
     sshpass \
     python3-pandas \
-    btrfs-progs
+    btrfs-progs \
+    iptables
 fi
 
 sudo mkdir -p /usr/src