Hello Apache Pulsar Community,
I'm Pulsar 2.8.1 release manager. When I try to build docker images on
branch-2.8, it failed with the following exception:
```
Error: The command '/bin/sh -c apt-get update && apt-get install
-y netcat dnsutils less procps iputils-ping python3.7
python3.7-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 && apt-get
clean && rm -rf /var/lib/apt/lists/*' returned a non-zero code: 100
```
The reason is that python3.7 is not available to install in the
openjdk:11-jdk image, which is used as a pulsar docker base image. The
build exception is: https://github.com/apache/pulsar/runs/3428234664
Thus, I cherry-pick PR#11026(https://github.com/apache/pulsar/pull/11026)
into branch-2.8 and will be released in pulsar 2.8.1. PR#11026 will use
ubuntu:20.04 base image for Pulsar docker images and use python3 instead of
python3.7.
If you have any questions, please let me know, thank you very much!
All The Best,
Hang
