chore: take care of correct mutex name in case assembly path is null …

…or empty

src/NUnitTestAdapter/NUnitEngine/NUnitEngineAdapter.cs

@@ -167,7 +167,7 @@ public void GenerateTestOutput(NUnitResults testResults, string assemblyPath, st
 
             var resultService = GetService<IResultService>();
 
-            using (Mutex mutex = new Mutex(false, assemblyPath))
+            using (Mutex mutex = new Mutex(false, string.IsNullOrWhiteSpace(assemblyPath) ? nameof(GenerateTestOutput) : assemblyPath))
             {
                 bool received = false;
                 try