Add "pinch_root" for Ghost Tree [ci skip]

Author: Rusty-Box

data/images/creatures/ghosttree/pinch_root.png

@@ -0,0 +1,7 @@
+(supertux-sprite
+  (action
+    (name "default")
+	(hitbox 37 37 16 188)
+    (images "pinch_root.png")
+  )
+)