UpdateManager.RestartApp fails when EntryAssembly is a dll

[jeremia]

We are using Squirrel.Windows in a WPF .NET Core 3 project.
It's working fine. We just had to add the Squirrel.dll and NuGet.Squirrel.dll manually to the project. The other nuget dependencies were added as normal nuget packages.

But when calling UpdateManager.Restart app it fails due to that Assembly.GetEntryAssembly() returns the dll for our WPF application, not our exe.

"Process.GetCurrentProcess().MainModule.FileName" works in our case and it is my understanding that it will always give the exe file of the main process, which is exactly what is wanted. See my pull request for this fix.