Introduce one more constant + cleanup

src/ImageSharp/Formats/Jpeg/Components/Decoder/HuffmanScanBuffer.cs

@@ -141,7 +141,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
         private ulong GetBytes()
         {
             ulong temp = 0;
-            for (int i = 0; i < 6; i++)
+            for (int i = 0; i < JpegConstants.Huffman.FetchLoop; i++)
             {
                 int b = this.ReadStream();
 

src/ImageSharp/Formats/Jpeg/JpegConstants.cs

@@ -255,6 +255,11 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
             /// </summary>
             public const int FetchBits = 48;
 
+            /// <summary>
+            /// The number of times to read the input stream when filling the <see cref="HuffmanScanBuffer"/> buffer.
+            /// </summary>
+            public const int FetchLoop = FetchBits / 8;
+
             /// <summary>
             /// The minimum number of bits allowed before by the <see cref="HuffmanScanBuffer"/> before fetching.
             /// </summary>

src/ImageSharp/Processing/Processors/ImageProcessor{TPixel}.cs

@@ -94,7 +94,7 @@ namespace SixLabors.ImageSharp.Processing.Processors
         }
 
         /// <inheritdoc/>
-        public virtual void Dispose()
+        public void Dispose()
         {
             this.Dispose(true);
             GC.SuppressFinalize(this);