Show old conferences in descending order
Show old conferences in descending order

It is more likely that users look for recent conferences.

Fixes https://github.com/openSUSE/osem/issues/2331

AndrewKvalheim/osem,rishabhptr/osem,SeaGL/osem,openSUSE/osem,SeaGL/osem,differentreality/osem,openSUSE/osem,AndrewKvalheim/osem,rishabhptr/osem,rishabhptr/osem,AndrewKvalheim/osem,differentreality/osem,hennevogel/osem,openSUSE/osem,hennevogel/osem,rishabhptr/osem,differentreality/osem,differentreality/osem,hennevogel/osem,hennevogel/osem,SeaGL/osem