Update to build with PowerShell SDK 6.2.0-preview.4 (#140)

Author: TylerLeonhardt

src/Microsoft.Azure.Functions.PowerShellWorker.csproj

@@ -18,7 +18,7 @@ Licensed under the MIT license. See LICENSE file in the project root for full li
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.PowerShell.SDK" Version="6.2.0-preview.3" />
+    <PackageReference Include="Microsoft.PowerShell.SDK" Version="6.2.0-preview.4" />
     <PackageReference Include="Newtonsoft.Json" Version="12.0.1" />
     <PackageReference Include="CommandLineParser" Version="2.3.0" />
     <PackageReference Include="Grpc" Version="1.14.1" />

test/Microsoft.Azure.Functions.PowerShellWorker.Test.csproj

@@ -11,7 +11,7 @@
     <PackageReference Include="xunit" Version="2.3.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
     <DotNetCliToolReference Include="dotnet-xunit" Version="2.3.1" />
-    <PackageReference Include="Microsoft.PowerShell.SDK" Version="6.2.0-preview.3" />
+    <PackageReference Include="Microsoft.PowerShell.SDK" Version="6.2.0-preview.4" />
   </ItemGroup>
 
   <ItemGroup>