Correct slot types for brewing stand. Fixes BUKKIT-3937

By: Travis Watkins <amaranth@ubuntu.com>

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventoryView.java

@@ -85,7 +85,7 @@ public class CraftInventoryView extends InventoryView {
                 }
                 break;
             case BREWING:
-                if (slot == 0) {
+                if (slot == 3) {
                     type = SlotType.FUEL;
                 } else {
                     type = SlotType.CRAFTING;