Use higher tolerance on macOS CI runs

tests/ImageSharp.Tests/Processing/Processors/Transforms/ResizeTests.cs

@@ -35,7 +35,8 @@ namespace SixLabors.ImageSharp.Tests.Processing.Processors.Transforms
                 nameof(KnownResamplers.Lanczos5),
             };
 
-        private static readonly ImageComparer ValidatorComparer = ImageComparer.TolerantPercentage(0.07F);
+        private static readonly ImageComparer ValidatorComparer =
+            ImageComparer.TolerantPercentage(TestEnvironment.IsOSX && TestEnvironment.RunsOnCI ? 0.2595F : 0.07F);
 
         [Fact]
         public void Resize_PixelAgnostic()

tests/ImageSharp.Tests/TestUtilities/TestEnvironment.cs

@@ -108,6 +108,8 @@ namespace SixLabors.ImageSharp.Tests
 
         internal static bool IsLinux => RuntimeInformation.IsOSPlatform(OSPlatform.Linux);
 
+        internal static bool IsOSX => RuntimeInformation.IsOSPlatform(OSPlatform.OSX);
+
         internal static bool IsMono => Type.GetType("Mono.Runtime") != null; // https://stackoverflow.com/a/721194
 
         internal static bool IsWindows => RuntimeInformation.IsOSPlatform(OSPlatform.Windows);