Update to Minecraft 1.13.1

By: md_5 <git@md-5.net>

paper-server/src/test/java/org/bukkit/BiomeTest.java

@@ -1,6 +1,7 @@
 package org.bukkit;
 
 import net.minecraft.server.BiomeBase;
+import net.minecraft.server.IRegistry;
 import org.bukkit.block.Biome;
 import org.bukkit.craftbukkit.block.CraftBlock;
 import org.bukkit.support.AbstractTestingBase;
@@ -18,7 +19,7 @@ public class BiomeTest extends AbstractTestingBase {
 
     @Test
     public void testMinecraftToBukkit() {
-        for (Object biome : BiomeBase.REGISTRY_ID) {
+        for (Object biome : IRegistry.BIOME) {
             Assert.assertNotNull("No Bukkit mapping for " + biome, CraftBlock.biomeBaseToBiome((BiomeBase) biome));
         }
     }