fix BmpDecoder_ThrowsException_Issue2696

Author: antonfirsov

tests/ImageSharp.Tests/Formats/Bmp/BmpDecoderTests.cs

@@ -563,8 +563,11 @@ public void BmpDecoder_CanDecode_Os2BitmapArray<TPixel>(TestImageProvider<TPixel
     [WithFile(Issue2696, PixelTypes.Rgba32)]
     public void BmpDecoder_ThrowsException_Issue2696<TPixel>(TestImageProvider<TPixel> provider)
         where TPixel : unmanaged, IPixel<TPixel>
-        => Assert.Throws<InvalidImageContentException>(() =>
-        {
-            using Image<TPixel> image = provider.GetImage(BmpDecoder.Instance);
-        });
+    {
+        InvalidImageContentException ex = Assert.Throws<InvalidImageContentException>(() =>
+            {
+                using Image<TPixel> image = provider.GetImage(BmpDecoder.Instance);
+            });
+        Assert.IsType<InvalidMemoryOperationException>(ex.InnerException);
+    }
 }

tests/Images/Input/Bmp/issue-2696.bmp

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:de7e7ec0454a55f6a76c859f356b240a3d4cb56ca50dfa209a1813dd09e12076
-size 143
+oid sha256:bc42cda9bac8fc73351ad03bf55214069bb8d31ea5bdd806321a8cc8b56c282e
+size 126