Fix off-by-one error in MinecraftCompressEncoder

proxy/src/main/java/com/velocitypowered/proxy/protocol/netty/MinecraftCompressEncoder.java

@@ -20,7 +20,7 @@ public class MinecraftCompressEncoder extends MessageToByteEncoder<ByteBuf> {
   @Override
   protected void encode(ChannelHandlerContext ctx, ByteBuf msg, ByteBuf out) throws Exception {
     int uncompressed = msg.readableBytes();
-    if (uncompressed <= threshold) {
+    if (uncompressed < threshold) {
       // Under the threshold, there is nothing to do.
       ProtocolUtils.writeVarInt(out, 0);
       out.writeBytes(msg);