increase version number of PackedTrack to reflect change in the definition of LHCbID

Workarounds have been added to convert the LHCbIDs in the tracks for older data to the new scheme.

Event/RecEvent/include/Event/RecVertex_v2.h

@@ -47,8 +47,8 @@ namespace LHCb::Event::v2 {
   struct WeightedTrack {
     using Track = LHCb::Event::v2::Track;
     WeightedTrack( const Track* t, float w ) : track( t ), weight( w ){};
-    const Track* track;
-    float        weight;
+    const Track* track  = nullptr;
+    float        weight = 0.0;
   };
 
   /// Reconstructed Vertices class