Fix Biome coordinate translation

src/main/java/com/moulberry/axiom/packet/SetBlockBufferPacketListener.java

@@ -88,7 +88,9 @@ public class SetBlockBufferPacketListener implements AxiomPacketListener {
         Set<Chunk> changedChunks = new HashSet<>();
         biomeBuffer.forEachEntry((x, y, z, biome) -> {
             world.setBiome(x*4, y*4, z*4, biome);
-            changedChunks.add(world.getChunkAt(x*4, z*4));
+            int cx = x/4 - (x < 0 ? 1 : 0);
+            int cz = z/4 - (z < 0 ? 1 : 0);
+            changedChunks.add(world.getChunkAt(cx, cz));
         });
 
         ServerLevel level = AxiomPaper.convert(world);