Explicitly update beatmap info wedge on mod change

This used to already be the case prior to b419ea7, but in a very
roundabout way. Changes to the value of the star difficulty bindable -
including indirect changes via the set of active mods changing - would
trigger the wedge display to regenerate and load asynchronously.

b419ea7 accidentally broke this by moving down the bindable retrieval to
a lower level, at which point `WedgeInfoText` would only receive the set
of mods selected at the time at which a given beatmap was selected, and
not receive any further updates, breaking the BPM display updating in
real time (as `WedgeInfoText` could not be aware that rate-changing mods
were even in effect).

To resolve, explicitly reload the wedge's contents on mod changes.

osu.Game/Screens/Select/BeatmapInfoWedge.cs

@@ -71,6 +71,7 @@ namespace osu.Game.Screens.Select
         private void load()
         {
             ruleset.BindValueChanged(_ => updateDisplay());
+            mods.BindValueChanged(_ => updateDisplay());
         }
 
         private const double animation_duration = 800;