Mark buffer builder fix as client only

Author: embeddedt

common/src/main/java/org/embeddedt/modernfix/common/mixin/bugfix/buffer_builder_leak/BufferBuilderMixin.java

@@ -2,6 +2,7 @@
 
 import com.mojang.blaze3d.vertex.BufferBuilder;
 import org.embeddedt.modernfix.ModernFix;
+import org.embeddedt.modernfix.annotation.ClientOnlyMixin;
 import org.embeddedt.modernfix.render.UnsafeBufferHelper;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.Shadow;
@@ -12,6 +13,7 @@
 import java.nio.ByteBuffer;
 
 @Mixin(BufferBuilder.class)
+@ClientOnlyMixin
 public class BufferBuilderMixin {
     @Shadow private ByteBuffer buffer;