Remove debug print

src/operator/Stack.cpp

@@ -68,9 +68,6 @@ void StackOpImpl::backward() {
     auto inputGrad = op.getInput(0)->grad();
     auto outputGrad = op.getOutput(0)->grad();
 
-    Log::notice("Size of stack in grad  : {}", inputGrad->size());
-    Log::notice("Size of stack out grad : {}", outputGrad->size());
-
     *inputGrad = outputGrad->extract({op.backwardStep() -1 }).clone();
 }