Add setter for DeflateCompressionLevel

Author: brianpopow

src/ImageSharp/Formats/Tiff/TiffEncoder.cs

@@ -21,7 +21,7 @@ public class TiffEncoder : IImageEncoder, ITiffEncoderOptions
         public TiffEncoderCompression Compression { get; set; } = TiffEncoderCompression.None;
 
         /// <inheritdoc/>
-        public DeflateCompressionLevel CompressionLevel { get; } = DeflateCompressionLevel.DefaultCompression;
+        public DeflateCompressionLevel CompressionLevel { get; set; } = DeflateCompressionLevel.DefaultCompression;
 
         /// <inheritdoc/>
         public TiffEncodingMode Mode { get; set; }