readme: remove useless badge

12 jobs for pr/103 in 1 minute and 30 seconds (queued for 5 seconds)
Status Name Job ID Coverage
  Test
passed doc-coverage #127163

00:01:20

passed format #127164

00:00:30

passed robotpkg-example-robot-data-18.04 #127153

00:00:24

passed robotpkg-example-robot-data-20.04 #127154

00:01:01

passed robotpkg-example-robot-data-buster #127155

00:00:27

passed robotpkg-example-robot-data-ferrum #127156

00:00:50

passed robotpkg-example-robot-data-stretch #127157

00:00:40

passed robotpkg-py-example-robot-data-18.04 #127158

00:01:07

passed robotpkg-py-example-robot-data-20.04 #127159

00:01:29

passed robotpkg-py-example-robot-data-buster #127160

00:01:20

passed robotpkg-py-example-robot-data-ferrum #127161

00:01:18

passed robotpkg-py-example-robot-data-stretch #127162

00:01:17