Add cast to half

ScriptableRenderPipeline/LightweightPipeline/LWRP/Shaders/LightweightSampling.shader

         s += (SAMPLE_TEXTURE2D(tex, samplerTex, uv + d.xw));
         s += (SAMPLE_TEXTURE2D(tex, samplerTex, uv + d.zw));
 
-        return s * 0.25;
+        return s * 0.25h;
     }
 
     ENDHLSL