[main] Update dependencies from dotnet/arcade (dotnet#10105)

* Update dependencies from https://github.com/dotnet/arcade build 20200909.8

Microsoft.DotNet.Arcade.Sdk
 From Version 5.0.0-beta.20453.7 -> To Version 5.0.0-beta.20459.8

* retain stable sdk

Co-authored-by: dotnet-maestro[bot] <dotnet-maestro[bot]@users.noreply.github.com>
Co-authored-by: Brett V. Forsgren <brettfo@microsoft.com>

Author: 2 people

eng/Version.Details.xml

@@ -3,9 +3,9 @@
   <ProductDependencies>
   </ProductDependencies>
   <ToolsetDependencies>
-    <Dependency Name="Microsoft.DotNet.Arcade.Sdk" Version="5.0.0-beta.20453.7">
+    <Dependency Name="Microsoft.DotNet.Arcade.Sdk" Version="5.0.0-beta.20459.8">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>16b71a2f216c3c5be5860977c4cb03a95ee2f0e3</Sha>
+      <Sha>91470b0b14ba016c1fb78211b12775287c17b34e</Sha>
     </Dependency>
   </ToolsetDependencies>
 </Dependencies>

global.json

@@ -12,7 +12,7 @@
     }
   },
   "msbuild-sdks": {
-    "Microsoft.DotNet.Arcade.Sdk": "5.0.0-beta.20453.7",
+    "Microsoft.DotNet.Arcade.Sdk": "5.0.0-beta.20459.8",
     "Microsoft.DotNet.Helix.Sdk": "2.0.0-beta.19069.2"
   }
 }