Fix: tzdata hangs Docker image build

tzdata.sh

Step 1/5 : FROM ubuntu:20.04
 ---> 1e4467b07108
Step 2/5 : ENV TZ=Asia/Dubai
 ---> Using cache
 ---> 7f4c85bd0d3e
Step 3/5 : RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
 ---> Using cache
 ---> f6f784dfbad5
Step 4/5 : RUN apt update
 ---> Using cache
 ---> 5b1b5617eaa5
Step 5/5 : RUN apt install -y tzdata
 ---> Running in e71a917a9b6b
Current default time zone: 'Asia/Dubai'
Local time is now:      Tue Aug  4 12:14:55 +04 2020.
Universal Time is now:  Tue Aug  4 08:14:55 UTC 2020.
Run 'dpkg-reconfigure tzdata' if you wish to change it.

Removing intermediate container e71a917a9b6b
 ---> 3d29f4e8f7eb
Successfully built 3d29f4e8f7eb
Successfully tagged tzdata:latest