Removed dashing from readme, because EOL

Signed-off-by: Nordmann Arne (CR/ADT3) <arne.nordmann@de.bosch.com>

Author: norro

README.md

@@ -1,7 +1,6 @@
 # ROS 2 System Modes
 
 [![License](https://img.shields.io/badge/License-Apache%202-blue.svg)](https://github.com/micro-ROS/system_modes/blob/master/LICENSE)
-[![Build status](https://build.ros2.org/job/Ddev__system_modes__ubuntu_bionic_amd64/badge/icon?subject=Build%20farm%3A%20Dashing)](https://build.ros2.org/job/Ddev__system_modes__ubuntu_bionic_amd64/)
 [![Build status](http://build.ros2.org/job/Fdev__system_modes__ubuntu_focal_amd64/badge/icon?subject=Build%20farm%3A%20Foxy)](http://build.ros2.org/job/Fdev__system_modes__ubuntu_focal_amd64/)
 [![Build status](http://build.ros2.org/job/Gdev__system_modes__ubuntu_focal_amd64/badge/icon?subject=Build%20farm%3A%20Galaxy)](http://build.ros2.org/job/Gdev__system_modes__ubuntu_focal_amd64/)
 [![Build status](http://build.ros2.org/job/Rdev__system_modes__ubuntu_focal_amd64/badge/icon?subject=Build%20farm%3A%20Rolling)](http://build.ros2.org/job/Rdev__system_modes__ubuntu_focal_amd64/)