jobs.yml: Build librem5-themes for all architectures

At the moment the package isn't any use for the nitrogen boards and it
would be good if it was.
1 job for librem5-themes-all-archs in 24 seconds (queued for 5 minutes and 5 seconds)
latest
Status Job ID Name Coverage
  Test
passed #1576
librem5
build-native

00:00:24