Ubuntu version updated to 20.04

Change-Id: I03dffeb5f1934828f0f8d85760a0b396373ae082
Signed-off-by: palsus <subhankar.pal@aricent.com>
(cherry picked from commit 9687207f24cc4ff95c6b0bd147d658c99c47ab93)
diff --git a/docker/POL/Dockerfile b/docker/POL/Dockerfile
index 879e91c..f143b62 100644
--- a/docker/POL/Dockerfile
+++ b/docker/POL/Dockerfile
@@ -20,14 +20,16 @@
 # contact: bdiaz@whitestack.com or glavado@whitestack.com
 ##
 
-FROM ubuntu:16.04
+FROM ubuntu:20.04
 
 LABEL authors="Benjamín Díaz"
 
-RUN apt-get --yes update \
- && apt-get --yes install git python python-pip python3 python3-pip libmysqlclient-dev libssl-dev libffi-dev \
- && apt-get --yes install mysql-client curl software-properties-common \
- && pip3 install pip==9.0.3
+RUN DEBIAN_FRONTEND=noninteractive apt-get -y update \
+ && DEBIAN_FRONTEND=noninteractive apt-get -y install \
+    git python3 python3-pip libmysqlclient-dev libssl-dev libffi-dev \
+    mysql-client curl software-properties-common
+
+RUN pip3 install pip==21.0.1
 
 ARG REPOSITORY_BASE=http://osm-download.etsi.org/repository/osm/debian
 ARG RELEASE=ReleaseNINE-daily
@@ -40,7 +42,8 @@
 ARG POL_VERSION
 ARG COMMON_VERSION
 
-RUN apt-get --yes update  && apt-get -y install python3-osm-policy-module${POL_VERSION}
+RUN DEBIAN_FRONTEND=noninteractive apt-get -y update \
+ && DEBIAN_FRONTEND=noninteractive apt-get -y install python3-osm-policy-module${POL_VERSION}
 
 COPY scripts/ scripts/