Fix HEIF tests after upstream merge

tests/ImageSharp.Tests/Formats/Heif/Av1/Av1TilingTests.cs

@@ -35,7 +35,7 @@ public class Av1TilingTests
 
         // Assert
         Assert.Equal(dataSize * 8, bitStreamReader.BitPosition);
-        Assert.False(frameBuffer.BufferY.Size().IsEmpty);
+        Assert.False(frameBuffer.BufferY.Size.IsEmpty);
         Assert.True(frameBuffer.BufferY.DangerousGetSingleSpan().ContainsAnyExcept<byte>(0));
     }
 

tests/ImageSharp.Tests/Formats/Heif/Av1/ObuFrameHeaderTests.cs

@@ -74,7 +74,7 @@ public class ObuFrameHeaderTests
 
         // Assert
         byte[] encodedArray = encoded.ToArray();
-        Assert.Equal(span, encodedArray);
+        Assert.Equal((ReadOnlySpan<byte>)span, encodedArray);
     }
 
     [Theory]