fix: replace NMS imports in tests with the correct ones

Author: JarvisCraft

PacketWrapper/src/test/java/com/comphenix/packetwrapper/TestWrappers.java

@@ -9,7 +9,7 @@
 import com.comphenix.protocol.utility.MinecraftVersion;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
-import net.minecraft.server.v1_15_R1.DispenserRegistry;
+import net.minecraft.server.v1_16_R3.DispenserRegistry;
 import org.bukkit.Bukkit;
 import org.bukkit.Server;
 import org.bukkit.World;

PacketWrapper/src/test/java/com/comphenix/packetwrapper/utils/ItemFactoryDelegate.java

@@ -20,7 +20,7 @@
 
 import org.bukkit.Color;
 import org.bukkit.Material;
-import org.bukkit.craftbukkit.v1_15_R1.inventory.CraftItemFactory;
+import org.bukkit.craftbukkit.v1_16_R3.inventory.CraftItemFactory;
 import org.bukkit.inventory.ItemFactory;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.inventory.meta.ItemMeta;