Pin version of charmed MongoDB to use channel latest/stable

Change-Id: I4d00dd4e01d92c27fee310f779c75808579ee193
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/installers/full_install_osm.sh b/installers/full_install_osm.sh
index ad46adc..a0007df 100755
--- a/installers/full_install_osm.sh
+++ b/installers/full_install_osm.sh
@@ -308,7 +308,7 @@
 function deploy_charmed_services() {
     [ -z "${DEBUG_INSTALL}" ] || DEBUG beginning of function
     juju add-model $OSM_NAMESPACE $OSM_VCA_K8S_CLOUDNAME
-    juju deploy ch:mongodb-k8s -m $OSM_NAMESPACE
+    juju deploy ch:mongodb-k8s -m $OSM_NAMESPACE --channel latest/stable
     [ -z "${DEBUG_INSTALL}" ] || DEBUG end of function
 }