Fix bug 1743: Pin juju version to 2.8.13

Change-Id: I51ce772e0d899d036e4dcb60c7008bc0a118d7da
Signed-off-by: David Garcia <david.garcia@canonical.com>
diff --git a/installers/full_install_osm.sh b/installers/full_install_osm.sh
index d7eec94..b43ff7d 100755
--- a/installers/full_install_osm.sh
+++ b/installers/full_install_osm.sh
@@ -1629,7 +1629,7 @@
 
 LXD_VERSION=4.0
 JUJU_VERSION=2.8
-JUJU_AGENT_VERSION=2.8.11
+JUJU_AGENT_VERSION=2.8.13
 UNINSTALL=""
 DEVELOP=""
 UPDATE=""