Use using declarations to reduce nesting

src/ImageSharp/Processing/Processors/Effects/OilPaintingProcessor{TPixel}.cs

@@ -5,7 +5,6 @@ using System;
 using System.Buffers;
 using System.Numerics;
 using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
 
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Advanced.ParallelUtils;
@@ -58,8 +57,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
 
             Configuration configuration = this.Configuration;
 
-            using (Buffer2D<TPixel> targetPixels = this.Configuration.MemoryAllocator.Allocate2D<TPixel>(source.Size()))
+            using Buffer2D<TPixel> targetPixels = this.Configuration.MemoryAllocator.Allocate2D<TPixel>(source.Size());
-            {
             source.CopyTo(targetPixels);
 
             var workingRect = Rectangle.FromLTRB(startX, startY, endX, endY);
@@ -69,8 +67,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
                 (rows) =>
                 {
                     // Rent the shared buffer only once per parallel item.
-                            using (IMemoryOwner<float> bins = configuration.MemoryAllocator.Allocate<float>(levels * 4))
+                    using IMemoryOwner<float> bins = configuration.MemoryAllocator.Allocate<float>(levels * 4);
-                            {
                     ref float binsRef = ref bins.GetReference();
                     ref int intensityBinRef = ref Unsafe.As<float, int>(ref binsRef);
                     ref float redBinRef = ref Unsafe.Add(ref binsRef, levels);
@@ -135,11 +132,9 @@ namespace SixLabors.ImageSharp.Processing.Processors.Effects
                             }
                         }
                     }
-                            }
                 });
 
             Buffer2D<TPixel>.SwapOrCopyContent(source.PixelBuffer, targetPixels);
         }
     }
 }
-}