add AssemblyInfo.cs

src/DotNetCore.CAP.MongoDB/Properties/AssemblyInfo.cs

@@ -0,0 +1,6 @@
+// Copyright (c) .NET Core Community. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("DotNetCore.CAP.MongoDB.Test")]