Merged PR 8353: [internal/release/3.1] Update dependencies from dnceng/internal/dotnet-efcore

This pull request updates the following dependencies

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## From https://github.com/dotnet/efcore
- **Subscription**: e908e90a-0c22-4c54-b254-08d79557a113
- **Build**: 20200609.7
- **Date Produced**: 6/9/2020 9:34 PM
- **Commit**: d2274a92d61afce64e4ee11b32e71a0476456703
- **Branch**: refs/heads/internal/release/3.1
- **Updates**:
  - **Microsoft.EntityFrameworkCore.Tools**: from 3.1.5 to 3.1.6
  - **Microsoft.EntityFrameworkCore.InMemory**: from 3.1.5 to 3.1.6
  - **Microsoft.EntityFrameworkCore**: from 3.1.5 to 3.1.6
  - **Microsoft.EntityFrameworkCore.Relational**: from 3.1.5 to 3.1.6
  - **Microsoft.EntityFrameworkCore.Sqlite**: from 3.1.5 to 3.1.6
  - **dotnet-ef**: from 3.1.5 to 3.1.6
  - **Microsoft.EntityFrameworkCore.SqlServer**: from 3.1.5 to 3.1.6

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Author: dotnet-bot

NuGet.config

@@ -4,6 +4,11 @@
     <clear />
     <!--Begin: Package sources managed by Dependency Flow automation. Do not edit the sources below.-->
     <add key="darc-pub-dotnet-corefx-8a3ffed" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/darc-pub-dotnet-corefx-8a3ffed5/nuget/v3/index.json" />
+    <add key="darc-int-dotnet-extensions-be18161" value="https://pkgs.dev.azure.com/dnceng/_packaging/darc-int-dotnet-extensions-be18161f/nuget/v3/index.json" />
+    <add key="darc-int-dotnet-efcore-509fe04" value="https://pkgs.dev.azure.com/dnceng/_packaging/darc-int-dotnet-efcore-509fe041/nuget/v3/index.json" />
+    <add key="darc-int-dotnet-core-setup-3acd9b0" value="https://pkgs.dev.azure.com/dnceng/_packaging/darc-int-dotnet-core-setup-3acd9b0c/nuget/v3/index.json" />
+    <add key="darc-int-dotnet-corefx-059a4a1" value="https://pkgs.dev.azure.com/dnceng/_packaging/darc-int-dotnet-corefx-059a4a19/nuget/v3/index.json" />
+    <add key="darc-int-dotnet-aspnetcore-tooling-0e01666" value="https://pkgs.dev.azure.com/dnceng/_packaging/darc-int-dotnet-aspnetcore-tooling-0e016665/nuget/v3/index.json" />
     <!--End: Package sources managed by Dependency Flow automation. Do not edit the sources above.-->
     <add key="dotnet-core" value="https://dotnetfeed.blob.core.windows.net/dotnet-core/index.json" />
     <add key="dotnet-eng" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/index.json" />