Pin libjuju version to 2.8.2

Fixes bug 1144

Change-Id: Ib50f76e45b9d429f019972c367b6692ed2d5ed79
Signed-off-by: Mark Beierl <mark.beierl@canonical.com>
(cherry picked from commit 2ed0e235700fcf05c0ff207d1a3f4f97f7302021)
diff --git a/docker/MON/Dockerfile b/docker/MON/Dockerfile
index 2b83148..29cc893 100644
--- a/docker/MON/Dockerfile
+++ b/docker/MON/Dockerfile
@@ -61,7 +61,7 @@
                           python3-n2vc${N2VC_VERSION}
 
 
-RUN python3 -m pip install -U "juju==2.8.1"
+RUN python3 -m pip install -U "juju==2.8.2"
 
 COPY scripts/ scripts/