Fix a reversed equals in Assert.

Author: StephenMolloy

src/SqlSessionStateProviderAsync/SqlCommandExtension.cs

@@ -13,7 +13,7 @@ public static SqlParameter GetOutPutParameterValue(this SqlCommand cmd, string p
             // This is an internal method that only we call. We know 'parameterName' always begins
             // with an '@' so we don't need to check for that case. Be aware of that expectation.
             Debug.Assert(parameterName != null);
-            Debug.Assert(parameterName[0] != '@');
+            Debug.Assert(parameterName[0] == '@');
             return cmd.Parameters[parameterName];
         }
     }