Mitigating dotnet 6 failure on ubuntu

[BenjaminMichaelis]

If the build and test action is switched to install dotnet 6.0 on ubuntu, a failure occurs as seen here: https://github.com/IntelliTect/EssentialCSharp/runs/7544380122?check_suite_focus=true

with this test (Listing20_09.Tests.ProgramTests.AsyncVoidReturnTest): https://github.com/IntelliTect/EssentialCSharp/runs/7544380122?check_suite_focus=true#step:7:587

[BenjaminMichaelis]

A copy of the failure:

Test run for /home/runner/work/EssentialCSharp/EssentialCSharp/src/Chapter20.Tests/bin/Debug/netcoreapp3.1/Chapter20.Tests.dll (.NETCoreApp,Version=v3.1)
Microsoft (R) Test Execution Command Line Tool Version 17.2.0 (x64)
Copyright (c) Microsoft Corporation.  All rights reserved.

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
  Failed AsyncVoidReturnTest [34 ms]
  Error Message:
   Test method AddisonWesley.Michaelis.EssentialCSharp.Chapter20.Listing20_09.Tests.ProgramTests.AsyncVoidReturnTest threw exception: 
System.Exception: The values are not like (using wildcards) each other:- 
-----------------------------------
Expected: "Invoking Task.Run...(Thread ID: *)\nRunning task... (Thread ID: *)\nPost notification invoked...(Thread ID: *)\nPost notification invoked...(Thread ID: *)\nThrowing expected exception....(Thread ID: *)\nSystem.Exception: Expected Exception\n   *(Thread ID: *)"
Actual  : "Invoking Task.Run...(Thread ID: 4)\nRunning task... (Thread ID: 10)\nPost notification invoked...(Thread ID: 4)\nThrowing expected exception....(Thread ID: 4)\nSystem.Exception: Expected Exception\n   at AddisonWesley.Michaelis.EssentialCSharp.Chapter20.Listing20_09.Program.<>c.<OnEvent>b__6_0() in /home/runner/work/EssentialCSharp/EssentialCSharp/src/Chapter20/Listing20.09.CatchingExceptionFromAsyncVoidMethod.cs:line 106\n   at System.Threading.Tasks.Task`1.InnerInvoke()\n   at System.Threading.Tasks.Task.<>c.<.cctor>b__274_0(Object obj)\n   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)\n--- End of stack trace from previous location where exception was thrown ---\n   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)\n   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)\n--- End of stack trace from previous location where exception was thrown ---\n   at AddisonWesley.Michaelis.EssentialCSharp.Chapter20.Listing20_09.Program.OnEvent(Object sender, EventArgs eventArgs) in /home/runner/work/EssentialCSharp/EssentialCSharp/src/Chapter20/Listing20.09.CatchingExceptionFromAsyncVoidMethod.cs:line 101\n   at System.Threading.Tasks.Task.<>c.<ThrowAsync>b__139_0(Object state)\n   at AddisonWesley.Michaelis.EssentialCSharp.Chapter20.Listing20_09.AsyncSynchronizationContext.Post(SendOrPostCallback callback, Object state) in /home/runner/work/EssentialCSharp/EssentialCSharp/src/Chapter20/Listing20.09.CatchingExceptionFromAsyncVoidMethod.cs:line 40\n--- End of stack trace from previous location where exception was thrown ---\n   at AddisonWesley.Michaelis.EssentialCSharp.Chapter20.Listing20_09.Program.Main() in /home/runner/work/EssentialCSharp/EssentialCSharp/src/Chapter20/Listing20.09.CatchingExceptionFromAsyncVoidMethod.cs:line 81 thrown as expected.(Thread ID: 4)"
-----------------------------------
The expected length of 253 does not match the output length of 2055. 
  Stack Trace:
      at IntelliTect.TestTools.Console.ConsoleAssert.AssertExpectation(String expectedOutput, String output, Func`3 areEquivalentOperator, String equivalentOperatorErrorMessage)
   at IntelliTect.TestTools.Console.ConsoleAssert.Execute(String givenInput, String expectedOutput, Action action, Func`3 areEquivalentOperator, NormalizeOptions normalizeOptions, String equivalentOperatorErrorMessage)
   at IntelliTect.TestTools.Console.ConsoleAssert.Expect(String expected, Action action, Func`3 comparisonOperator, NormalizeOptions normalizeOptions, String equivalentOperatorErrorMessage)
   at IntelliTect.TestTools.Console.ConsoleAssert.ExpectLike(String expected, Action action, NormalizeOptions normalizeLineEndings, Char escapeCharacter)
   at AddisonWesley.Michaelis.EssentialCSharp.Chapter20.Listing20_09.Tests.ProgramTests.AsyncVoidReturnTest() in /home/runner/work/EssentialCSharp/EssentialCSharp/src/Chapter20.Tests/Listing20.09.ImplementingCustomAsynchronousMethod.Tests.cs:line 21


Failed!  - Failed:     1, Passed:    24, Skipped:     0, Total:    25, Duration: 7 s - /home/runner/work/EssentialCSharp/EssentialCSharp/src/Chapter20.Tests/bin/Debug/netcoreapp3.1/Chapter20.Tests.dll (netcoreapp3.1)