Use fmt::print instead of printf

src/operator/ConcatImpl.cpp

@@ -87,4 +87,4 @@ void  Aidge::ConcatImpl_cpu::forward() {
                getCPUPtr(mOp.getRawOutput(0)));
 }
 
-void  Aidge::ConcatImpl_cpu::backward() { printf("Not implemented yet.\n"); }
+void  Aidge::ConcatImpl_cpu::backward() { fmt::print("Not implemented yet.\n"); }
\ No newline at end of file

src/operator/SliceImpl.cpp

@@ -79,4 +79,4 @@ void Aidge::SliceImpl_cpu::forward() {
     mNbProducedData[0] += getRequiredMemory(0, {});
 }
 
-void Aidge::SliceImpl_cpu::backward() { printf("Not implemented yet.\n"); }
+void Aidge::SliceImpl_cpu::backward() { fmt::print("Not implemented yet.\n"); }