AllocateSingleMemoryOwner_Finalization_ReturnsToPool test fails on mac os

[brianpopow]

Prerequisites

• I have written a descriptive issue title
• I have verified that I am running the latest version of ImageSharp
• I have verified if the problem exist in both DEBUG and RELEASE mode
• I have searched open and closed issues to ensure it has not already been reported

Description

AllocateSingleMemoryOwner_Finalization_ReturnsToPool fails only on mac os.

Steps to Reproduce

Run the tests on the CI.

System Configuration

• ImageSharp version: current master branch.
• Environment (Operating system, version and so on): MacOS
• .NET Framework version: net6.0 (not sure if it only happens on net6.0 or on other frameworks, too)
• Additional information:

AllocateMemoryGroup_Finalization_ReturnsToPool(length: 1200) [FAIL]
[xUnit.net 00:02:15.34]     AllocateMemoryGroup_Finalization_ReturnsToPool(length: 600) [FAIL]
  Failed AllocateMemoryGroup_Finalization_ReturnsToPool(length: 1200) [286 ms]
  Error Message:
   Microsoft.DotNet.RemoteExecutor.RemoteExecutionException : Remote process failed with an unhandled exception.
  Stack Trace:
  
Child exception:
  Xunit.Sdk.EqualException: Assert.Equal() Failure
Expected: 42
Actual:   0
   at SixLabors.ImageSharp.Tests.Memory.Allocators.UniformUnmanagedPoolMemoryAllocatorTests.AllocateGroupAndForget(UniformUnmanagedMemoryPoolMemoryAllocator allocator, Int32 length, Boolean check) in /Users/runner/work/ImageSharp/ImageSharp/tests/ImageSharp.Tests/Memory/Allocators/UniformUnmanagedPoolMemoryAllocatorTests.cs:line 299
   at SixLabors.ImageSharp.Tests.Memory.Allocators.UniformUnmanagedPoolMemoryAllocatorTests.<AllocateMemoryGroup_Finalization_ReturnsToPool>g__RunTest|12_0(String lengthStr) in /Users/runner/work/ImageSharp/ImageSharp/tests/ImageSharp.Tests/Memory/Allocators/UniformUnmanagedPoolMemoryAllocatorTests.cs:line 283

Child process:
  SixLabors.ImageSharp.Tests, Version=1.0.0.0, Culture=neutral, PublicKeyToken=d998eea7b14cab13 SixLabors.ImageSharp.Tests.Memory.Allocators.UniformUnmanagedPoolMemoryAllocatorTests Void <AllocateMemoryGroup_Finalization_ReturnsToPool>g__RunTest|12_0(System.String)

Child arguments:
  1200

  Failed AllocateMemoryGroup_Finalization_ReturnsToPool(length: 600) [538 ms]
  Error Message:
   Microsoft.DotNet.RemoteExecutor.RemoteExecutionException : Remote process failed with an unhandled exception.
  Stack Trace:
  
Child exception:
  Xunit.Sdk.EqualException: Assert.Equal() Failure
Expected: 42
Actual:   0
   at SixLabors.ImageSharp.Tests.Memory.Allocators.UniformUnmanagedPoolMemoryAllocatorTests.<AllocateMemoryGroup_Finalization_ReturnsToPool>g__RunTest|12_0(String lengthStr) in /Users/runner/work/ImageSharp/ImageSharp/tests/ImageSharp.Tests/Memory/Allocators/UniformUnmanagedPoolMemoryAllocatorTests.cs:line 290

[brianpopow]

Test AllocateMemoryGroup_Finalization_ReturnsToPool may also be affected by this