Depends on workspace-full-vnc

[esatbayhan]

Problem:
The gitpod configuration of this project depends on the dockerfile workspace-full-vnc by gitpod. Currently it uses Ubuntu 20.04 as distribution. This workspace depends on ROS2 foxy and works only on Ubuntu 20.04. If workspace-full-vnc changes the distribution from Ubuntu 20.04 this workspace will likely not function anymore.

Probable Solution:
Change image in .gitpod.yml to a customized Docker image with Ubuntu 20.04