Let all packages depending on tinydm depend on tinydm-openrc too. This
is needed to make sure that tinydm-openrc is installed, before the
tinydm service is enabled in the UI's post-install scripts.
This was not an issue because tinydm currently depends on tinydm-openrc.
But that's a hack and will be removed when upstreaming tinydm to alpine.
[ci:skip-build]: already built successfully in CI
