Fix: Beacon effects broken since 1.20.2 (#4199)

Since 1.20.2, effect IDs start at 0, not 1. Bedrock of course doesn't respect that, so we need to subtract 1!

core/src/main/java/org/geysermc/geyser/translator/inventory/BeaconInventoryTranslator.java

@@ -119,7 +119,7 @@ public class BeaconInventoryTranslator extends AbstractBlockInventoryTranslator
     }
 
     private OptionalInt toJava(int effectChoice) {
-        return effectChoice == 0 ? OptionalInt.empty() : OptionalInt.of(effectChoice);
+        return effectChoice == 0 ? OptionalInt.empty() : OptionalInt.of(effectChoice - 1);
     }
 
     @Override