Fix cffi version to match the latest stable

Change-Id: Id0e956bd07f0ca12df9375d6cc85c83aa2837334
Signed-off-by: David Garcia <david.garcia@canonical.com>
diff --git a/docker/LCM/Dockerfile b/docker/LCM/Dockerfile
index 145a251..11dd71d 100644
--- a/docker/LCM/Dockerfile
+++ b/docker/LCM/Dockerfile
@@ -42,7 +42,7 @@
     && pip3 install -U aiokafka pyang lxml six enum34 \
     && pip3 install websockets==4.0.1 \
     && pip3 install requests \
-    && pip3 install cffi==1.5.2 \
+    && pip3 install cffi==1.13.2 \
     && rm -rf /var/lib/apt/lists/*
 
 # packages needed for N2VC because deb dependencies are not fine