pgraph: Remove deprecated `PandaNode::set_bound()` method

It's been deprecated with warning for so long, with easy replacement

panda/src/pgraph/pandaNode.cxx

@@ -1860,16 +1860,6 @@ set_bounds(const BoundingVolume *volume) {
   CLOSE_ITERATE_CURRENT_AND_UPSTREAM(_cycler);
 }
 
-/**
- * @deprecated Use set_bounds() instead.
- */
-void PandaNode::
-set_bound(const BoundingVolume *volume) {
-  pgraph_cat.warning()
-    << "Deprecated PandaNode::set_bound() called.  Use set_bounds() instead.\n";
-  set_bounds(volume);
-}
-
 /**
  * Returns the external bounding volume of this node: a bounding volume that
  * contains the user bounding volume, the internal bounding volume, and all of

panda/src/pgraph/pandaNode.h

@@ -290,7 +290,6 @@ PUBLISHED:
   MAKE_PROPERTY(bounds_type, get_bounds_type);
 
   void set_bounds(const BoundingVolume *volume);
-  void set_bound(const BoundingVolume *volume);
   INLINE void clear_bounds();
   CPT(BoundingVolume) get_bounds(Thread *current_thread = Thread::get_current_thread()) const;
   CPT(BoundingVolume) get_bounds(UpdateSeq &seq, Thread *current_thread = Thread::get_current_thread()) const;