Fix bug 953: Fix version of cffi

Change-Id: I06445defdbfffeb11fbfd450823470ca4f7847cb
Signed-off-by: David Garcia <david.garcia@canonical.com>
diff --git a/docker/LCM/Dockerfile b/docker/LCM/Dockerfile
index 7a1f4a2..f141f92 100644
--- a/docker/LCM/Dockerfile
+++ b/docker/LCM/Dockerfile
@@ -78,6 +78,8 @@
 RUN curl ${REPOSITORY_BASE}/${RELEASE}/${REPOSITORY_KEY} | apt-key add -
 RUN add-apt-repository -y "deb ${REPOSITORY_BASE}/${RELEASE} ${REPOSITORY} LCM N2VC common" && apt update
 
+RUN python3 -m pip install -U "cffi==1.13.2"
+
 ARG LCM_VERSION
 ARG COMMON_VERSION
 ARG N2VC_VERSION