Pin juju version to 2.8.8

Change-Id: Ifa3b66d489adfd2522814d07a99886b35492dc67
Signed-off-by: David Garcia <david.garcia@canonical.com>
diff --git a/installers/full_install_osm.sh b/installers/full_install_osm.sh
index 3c0f4a7..a037854 100755
--- a/installers/full_install_osm.sh
+++ b/installers/full_install_osm.sh
@@ -1548,7 +1548,7 @@
     DOCKER_REGISTRY_URL=$(echo "$DOCKER_REGISTRY_URL" | awk '{split($1,a,"@"); print a[2]}')
 }
 
-JUJU_AGENT_VERSION=2.8.6
+JUJU_AGENT_VERSION=2.8.8
 UNINSTALL=""
 DEVELOP=""
 UPDATE=""