[master] Update dependencies from dotnet/arcade (#326)

* Update dependencies from https://github.com/dotnet/arcade build 20200928.3

Microsoft.DotNet.Arcade.Sdk , Microsoft.DotNet.Helix.Sdk
 From Version 5.0.0-beta.20474.4 -> To Version 5.0.0-beta.20478.3

* Do not roll Helix SDK back

* Do not roll Helix SDK back

Co-authored-by: dotnet-maestro[bot] <dotnet-maestro[bot]@users.noreply.github.com>
Co-authored-by: Premek Vysoky <premek.vysoky@microsoft.com>

eng/Version.Details.xml

@@ -3,9 +3,9 @@
   <ProductDependencies>
   </ProductDependencies>
   <ToolsetDependencies>
-    <Dependency Name="Microsoft.DotNet.Arcade.Sdk" Version="5.0.0-beta.20474.4">
+    <Dependency Name="Microsoft.DotNet.Arcade.Sdk" Version="5.0.0-beta.20478.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>61cde6e8fb9d5c9790867b279deb41783a780cd8</Sha>
+      <Sha>c8a7611e15656f45b039d46ec4e09f9f2a7edf99</Sha>
     </Dependency>
     <Dependency Name="Microsoft.DotNet.Helix.Sdk" Version="5.0.0-beta.20502.2">
       <Uri>https://github.com/dotnet/arcade</Uri>

global.json

@@ -3,7 +3,7 @@
     "dotnet": "5.0.100-rc.1.20452.10"
   },
   "msbuild-sdks": {
-    "Microsoft.DotNet.Arcade.Sdk": "5.0.0-beta.20474.4",
+    "Microsoft.DotNet.Arcade.Sdk": "5.0.0-beta.20478.3",
     "Microsoft.DotNet.Helix.Sdk": "5.0.0-beta.20502.2"
   }
 }