Fix IndexOutOfBoundsException on BlockFertilizeEvent (#4609)

Author: SirYwell

Bukkit/src/main/java/com/plotsquared/bukkit/listener/BlockEventListener117.java

@@ -134,7 +134,7 @@ public void onBlockReceiveGame(BlockReceiveGameEvent event) {
     public void onBlockFertilize(BlockFertilizeEvent event) {
         Block block = event.getBlock();
         List<org.bukkit.block.BlockState> blocks = event.getBlocks();
-        Location location = BukkitUtil.adapt(blocks.get(0).getLocation());
+        Location location = BukkitUtil.adapt(block.getLocation());
 
         PlotArea area = location.getPlotArea();
         if (area == null) {