fix test build

Author: VSadov

src/tests/async/valuetask-source/valuetask-source-stub.cs

@@ -41,7 +41,7 @@ public ValueTaskSourceStatus GetStatus(short token)
 
             public void OnCompleted(Action<object> continuation, object state, short token, ValueTaskSourceOnCompletedFlags flags)
             {
-                Assert.Equals(flags == ValueTaskSourceOnCompletedFlags.UseSchedulingContext);
+                Assert.Equal(ValueTaskSourceOnCompletedFlags.UseSchedulingContext, flags);
             }
         }
     }