Change apt_mk_version to testing

Change-Id: Ia958f9bdeac814313b0a0aacd0183f4a14dcf46a
diff --git a/classes/cluster/virtual-mcp11-aio/infra/init.yml b/classes/cluster/virtual-mcp11-aio/infra/init.yml
index 46d0de0..4a9170f 100644
--- a/classes/cluster/virtual-mcp11-aio/infra/init.yml
+++ b/classes/cluster/virtual-mcp11-aio/infra/init.yml
@@ -1,4 +1,4 @@
 parameters:
   _param:
-    apt_mk_version: stable
+    apt_mk_version: testing
     linux_system_purge_repos: false