Bug 1730: Assembly is not signed

https://winscp.net/tracker/1730

Re-enabling code signing that was lost by d49ae8072b0.

Source commit: b9b120cc94e7be688e7ced0ce46d2e1e2a0bdc94

dotnet/WinSCPnet.csproj

@@ -5,6 +5,8 @@
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <OutputPath>bin\$(Configuration)</OutputPath>
+    <SignAssembly>false</SignAssembly>
+    <AssemblyOriginatorKeyFile></AssemblyOriginatorKeyFile>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard2.0'">
     <DefineConstants>NETSTANDARD</DefineConstants>