Merged PR 44051: [internal/release/8.0] Updated NuGet.config - add feed for efcore 3b21bdbc

[internal/release/8.0] Updated NuGet.config - add feed for efcore 3b21bdbc

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#### AI description  (iteration 1)
#### PR Classification
Configuration update to add a new package feed.

#### PR Summary
This pull request updates the `NuGet.config` file to include a new package feed for efcore.
- `NuGet.config`: Added a new package source for `darc-int-dotnet-efcore-3b21bdbc`.

Author: vseanreesermsft

NuGet.config

@@ -6,6 +6,7 @@
     <!--  Begin: Package sources from dotnet-extensions -->
     <!--  End: Package sources from dotnet-extensions -->
     <!--  Begin: Package sources from dotnet-efcore -->
+    <add key="darc-int-dotnet-efcore-3b21bdbc" value="https://pkgs.dev.azure.com/dnceng/internal/_packaging/darc-int-dotnet-efcore-3b21bdbc/nuget/v3/index.json" />
     <!--  End: Package sources from dotnet-efcore -->
     <!--  Begin: Package sources from dotnet-runtime -->
     <add key="darc-int-dotnet-runtime-9cb3b72" value="https://pkgs.dev.azure.com/dnceng/internal/_packaging/darc-int-dotnet-runtime-9cb3b725/nuget/v3/index.json" />
@@ -36,6 +37,7 @@
     <clear />
     <!--Begin: Package sources managed by Dependency Flow automation. Do not edit the sources below.-->
     <!--  Begin: Package sources from dotnet-efcore -->
+    <add key="darc-int-dotnet-efcore-3b21bdbc" value="true" />
     <!--  End: Package sources from dotnet-efcore -->
     <!--  Begin: Package sources from dotnet-runtime -->
     <add key="darc-int-dotnet-runtime-05e0f2d" value="true" />