Use MSTest.SDK

[stan-sz]

https://aka.ms/mstest/sdk

After:

Passed! - Failed: 0, Passed: 15, Skipped: 0, Total: 15, Duration: 5m 48s 901ms

Before:

Passed!  - Failed:     0, Passed:    15, Skipped:     0, Total:    15, Duration: 6 m 11 s - Microsoft.CopyOnWrite.Tests.32bit.dll (net8.0)
Passed!  - Failed:     0, Passed:    15, Skipped:     0, Total:    15, Duration: 6 m 6 s - Microsoft.CopyOnWrite.Tests.dll (net8.0)

[stan-sz]

actions/setup-dotnet#72

[erikmav]

#56 addresses the outdated .NET 6 output and fixes the break in the exception class.