fix(pm/fava): remove unrealized plugin

Since a while back this plugin has been deprecated. We should remove it
to avoid the error...

packetmix/systems/teal/fava.nix

···
         plugin "fava.plugins.link_documents"
 
         plugin "beancount.plugins.pedantic"
-        plugin "beancount.plugins.unrealized" "Unrealized"
         plugin "beancount.plugins.implicit_prices"
 
         plugin "beancount_share.share" "{