chore: increase warmup count for flaky test (#2903)

Author: filzrev

tests/BenchmarkDotNet.IntegrationTests/MemoryDiagnoserTests.cs

@@ -245,7 +245,7 @@ public void AllocationQuantumIsNotAnIssueForNetCore21Plus(IToolchain toolchain)
             long objectAllocationOverhead = IntPtr.Size * 2; // pointer to method table + object header word
             long arraySizeOverhead = IntPtr.Size; // array length
             int warmupCount = OsDetector.IsMacOS()
-                ? 5  // Workaround setting for macos. https://github.com/dotnet/BenchmarkDotNet/issues/2779
+                ? 10 // Workaround setting for macos. https://github.com/dotnet/BenchmarkDotNet/issues/2779
                 : 0; // Other OS don't need warmup
 
             AssertAllocations(toolchain, typeof(TimeConsuming), new Dictionary<string, long>