skip ToVector4SimdAligned() test in environments without SIMD

tests/ImageSharp.Tests/PixelFormats/PixelOperationsTests.cs

@@ -31,6 +31,11 @@ namespace SixLabors.ImageSharp.Tests.PixelFormats
             [Fact]
             public void ToVector4SimdAligned()
             {
+                if (!Vector.IsHardwareAccelerated)
+                {
+                    return;
+                }
+
                 ImageSharp.PixelFormats.Rgba32[] source = CreatePixelTestData(64);
                 Vector4[] expected = CreateExpectedVector4Data(source);
 

tests/ImageSharp.Tests/TestUtilities/TestEnvironment.cs

@@ -95,6 +95,8 @@ namespace SixLabors.ImageSharp.Tests
 
         internal static bool IsWindows => RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
 
+        internal static bool Is64BitProcess => IntPtr.Size == 8;
+
         /// <summary>
         /// Creates the image output directory.
         /// </summary>