[Security] Install Ubuntu updates while building docker image

(cherry picked from commit 00b4dd4)

Author: lhotari

docker/pulsar/Dockerfile

@@ -52,12 +52,15 @@ FROM adoptopenjdk:11-jdk
 RUN groupadd -g 10001 pulsar
 RUN adduser -u 10000 --gid 10001 --disabled-login --disabled-password --gecos '' pulsar
 
-# Install some utilities
-RUN apt-get update \
+# Install upgrades and some utilities
+RUN DEBIAN_FRONTEND=noninteractive apt-get update \
+     && apt-get -y dist-upgrade \
      && apt-get install -y netcat dnsutils less procps iputils-ping \
                  python3 python3-dev python3-setuptools python3-yaml python3-kazoo \
                  libreadline-gplv2-dev libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev \
                  curl vim net-tools unzip \
+     && apt-get -y --purge autoremove \
+     && apt-get autoclean \
      && apt-get clean \
      && rm -rf /var/lib/apt/lists/*