Make approxEq take const ref

include/aidge/utils/TensorUtils.hpp

@@ -33,7 +33,7 @@ namespace Aidge {
  * @return true if both tensor are approximately equal and have the datatype, shape. Else return false
  */
 template <typename T1, typename T2 = T1>
-bool approxEq(Aidge::Tensor t1, Aidge::Tensor t2, float relative, float absolute){
+bool approxEq(const Tensor& t1, const Tensor& t2, float relative, float absolute){
     assert(t1.dataType() == NativeType<T1>::type);
     assert(t2.dataType() == NativeType<T2>::type);
     assert(relative >= 0);