remove redundant sum variable

Author: SimonCropp

src/ImageSharp/Processing/Processors/Transforms/TransformKernelMap.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors and contributors.
+// Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
 using System;
@@ -130,11 +130,9 @@ public void Convolve<TPixel>(
         [MethodImpl(InliningOptions.ShortMethod)]
         private void CalculateWeights(int min, int max, float point, ref float weightsRef)
         {
-            float sum = 0;
             for (int x = 0, i = min; i <= max; i++, x++)
             {
                 float weight = this.sampler.GetValue(i - point);
-                sum += weight;
                 Unsafe.Add(ref weightsRef, x) = weight;
             }
         }
@@ -158,4 +156,4 @@ public void Dispose()
             this.xBuffer?.Dispose();
         }
     }
-}
+}