Missing extra/xorg-server-xvfb from the dependencies

Description:

xpra throws random errors/cannot shadow due to missing xvfb

While starting a session works (e.g. xpra start ssh://user@10.1.1.215/ --start=gnome-terminal resuming with shadow fails with

xpra initialization error:
 cannot find live server for display 3

(for reference other people are observing this when the xvfb is not installed see for example https://github.com/kaueraal/run_scaled/issues/15 )

both server and client are arch running the exact same versions

Additional info:

applies to extra/xpra 6.2.1-2 [installed]

Steps to reproduce:

1. on a freshly installed system install xpra
2. connect to a remote server using xpra
3. try to xrpa shadow