Add unittest for net6 bug

ImageSharp.sln

@@ -403,6 +403,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "issues", "issues", "{670DD4
 		tests\Images\Input\Png\issues\Issue_1127.png = tests\Images\Input\Png\issues\Issue_1127.png
 		tests\Images\Input\Png\issues\Issue_1177_1.png = tests\Images\Input\Png\issues\Issue_1177_1.png
 		tests\Images\Input\Png\issues\Issue_1177_2.png = tests\Images\Input\Png\issues\Issue_1177_2.png
+		tests\Images\Input\Png\issues\Issue_1765_Net6DeflateStreamRead.png = tests\Images\Input\Png\issues\Issue_1765_Net6DeflateStreamRead.png
 		tests\Images\Input\Png\issues\Issue_410.png = tests\Images\Input\Png\issues\Issue_410.png
 		tests\Images\Input\Png\issues\Issue_935.png = tests\Images\Input\Png\issues\Issue_935.png
 	EndProjectSection

tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.cs

@@ -368,6 +368,24 @@ public void Issue1047<TPixel>(TestImageProvider<TPixel> provider)
             Assert.Null(ex);
         }
 
+        // https://github.com/SixLabors/ImageSharp/issues/1765
+        [Theory]
+        [WithFile(TestImages.Png.Issue1765_Net6DeflateStreamRead, PixelTypes.Rgba32)]
+        public void Issue1765<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            System.Exception ex = Record.Exception(
+                () =>
+                {
+                    using (Image<TPixel> image = provider.GetImage(PngDecoder))
+                    {
+                        image.DebugSave(provider);
+                        image.CompareToOriginal(provider, ImageComparer.Exact);
+                    }
+                });
+            Assert.Null(ex);
+        }
+
         // https://github.com/SixLabors/ImageSharp/issues/410
         [Theory]
         [WithFile(TestImages.Png.Bad.Issue410_MalformedApplePng, PixelTypes.Rgba32)]

tests/ImageSharp.Tests/TestImages.cs

@@ -111,6 +111,9 @@ public static class Png
             // Issue 935: https://github.com/SixLabors/ImageSharp/issues/935
             public const string Issue935 = "Png/issues/Issue_935.png";
 
+            // Issue 1765: https://github.com/SixLabors/ImageSharp/issues/1765
+            public const string Issue1765_Net6DeflateStreamRead = "Png/issues/Issue_1765_Net6DeflateStreamRead.png";
+
             public static class Bad
             {
                 public const string MissingDataChunk = "Png/xdtn0g01.png";