Fix clip implementation + add ReLU int8.

Fix clip implementation which was always converting input to float32. Now min and max are converted to input type.

• add ReLU int8.

include/aidge/backend/cpu/operator/ClipImpl_kernels.hpp

@@ -23,13 +23,14 @@ void ClipImpl_cpu_forward_kernel(
         float max_,
         const void* input_,
         const std::size_t length,
-        void* output_) 
+        void* output_)
 {
     const I* input = static_cast<const I*>(input_);
     O* output = static_cast<O*>(output_);
-
+    I minCasted = static_cast<I>(min_);
+    I maxCasted = static_cast<I>(max_);
     for (std::size_t i = 0; i < length; ++i) {
-        output[i] = std::min(std::max(static_cast<float>(input[i]), min_), max_);
+        output[i] = std::min(std::max(input[i], minCasted), maxCasted);
     }
 }
 
@@ -38,9 +39,9 @@ void ClipImpl_cpu_backward_kernel(
         float min_,
         float max_,
         const std::size_t length,
-        const void* input_, 
+        const void* input_,
         const void* grad_output_,
-		void* grad_input_)           
+		void* grad_input_)
 {
     const I* input = static_cast<const I*>(input_);
     const GO* grad_output = static_cast<const GO*>(grad_output_);