Add EntropyPasses default value explicit to 1

src/ImageSharp/Formats/Webp/IWebpEncoderOptions.cs

@@ -35,6 +35,7 @@ namespace SixLabors.ImageSharp.Formats.Webp
 
         /// <summary>
         /// Gets the number of entropy-analysis passes (in [1..10]).
+        /// Defaults to 1.
         /// </summary>
         int EntropyPasses { get; }
 

src/ImageSharp/Formats/Webp/WebpEncoder.cs

@@ -27,7 +27,7 @@ namespace SixLabors.ImageSharp.Formats.Webp
         public bool UseAlphaCompression { get; set; }
 
         /// <inheritdoc/>
-        public int EntropyPasses { get; set; }
+        public int EntropyPasses { get; set; } = 1;
 
         /// <inheritdoc/>
         public int SpatialNoiseShaping { get; set; } = 50;