Bumping .NET assembly version number before 5.14.2 release as there were changes

Source commit: ff138659e4da468c26cfe7bfdc826a325dc54cc9

dotnet/properties/AssemblyInfo.cs

@@ -35,7 +35,7 @@ namespace WinSCP
     {
         public const string UndefinedProductVersion = "9.9.9.9";
 
-        public const string Version = "1.6.0.0";
+        public const string Version = "1.6.1.0";
         public const string ProductVersion = "5.14.2.0";
     }
 }