Merge branch 'maintenance' into 'master'

ci: use node:12 as base

See merge request !56
4 jobs for release in 9 minutes and 28 seconds (queued for 9 minutes and 9 seconds)
Status Name Job ID Coverage
  Build
passed build #57174

00:06:15

 
  Test
passed lint #57177

00:00:18

passed test:chrome #57175

00:01:40

passed test:firefox #57176

00:02:13