Update dependencies from https://github.com/dotnet/aspnetcore build 20200821.6 (#13504)

[release/3.1.4xx] Update dependencies from dotnet/aspnetcore
- Updates:
  - Microsoft.AspNetCore.DeveloperCertificates.XPlat: from 3.1.8-servicing.20420.21 to 3.1.8-servicing.20421.6

Author: dotnet-maestro[bot]

eng/Version.Details.xml

@@ -31,9 +31,9 @@
       <Uri>https://dev.azure.com/dnceng/internal/_git/dotnet-corefx</Uri>
       <Sha>059a4a19e602494bfbed473dbbb18f2dbfbd0878</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.AspNetCore.DeveloperCertificates.XPlat" Version="3.1.8-servicing.20420.21">
+    <Dependency Name="Microsoft.AspNetCore.DeveloperCertificates.XPlat" Version="3.1.8-servicing.20421.6">
       <Uri>https://github.com/dotnet/aspnetcore</Uri>
-      <Sha>00bfa1bfa99bc72ddc43033e186b214369e8a613</Sha>
+      <Sha>c75b3f7a2fb9fe21fd96c93c070fdfa88a2fbe97</Sha>
     </Dependency>
     <!-- Keep this dependency at the bottom of ProductDependencies, else it will be picked as the parent for CoherentParentDependencies -->
     <Dependency Name="Microsoft.NETCore.App.Ref" Version="3.1.0" Pinned="true">

eng/Versions.props

@@ -28,7 +28,7 @@
   </PropertyGroup>
   <PropertyGroup>
     <!-- Dependencies from https://github.com/aspnet/AspNetCore -->
-    <MicrosoftAspNetCoreDeveloperCertificatesXPlatPackageVersion>3.1.8-servicing.20420.21</MicrosoftAspNetCoreDeveloperCertificatesXPlatPackageVersion>
+    <MicrosoftAspNetCoreDeveloperCertificatesXPlatPackageVersion>3.1.8-servicing.20421.6</MicrosoftAspNetCoreDeveloperCertificatesXPlatPackageVersion>
   </PropertyGroup>
   <PropertyGroup>
     <!-- Dependencies from https://github.com/microsoft/msbuild -->