Fix to allow debugging Visual Studio 2019 Preview

Use VsixTesting.Installer 0.1.46-beta which includes debugging fix.

No need for VsixTesting.Installer path workaround

Author: jcansdale

test/Launcher/InstallAndStart.csproj

@@ -3,7 +3,7 @@
     <TargetFramework>net461</TargetFramework>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="VsixTesting.Installer" Version="0.1.38-beta-g6b91b368d9" />
+    <PackageReference Include="VsixTesting.Installer" Version="0.1.46-beta-g3578f97a2e" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\src\GitHub.VisualStudio\GitHub.VisualStudio.csproj" />