[main] Update dependencies from dotnet/source-build-externals (#4473)

Co-authored-by: dotnet-maestro[bot] <dotnet-maestro[bot]@users.noreply.github.com>

Author: dotnet-maestro[bot]

eng/Version.Details.xml

@@ -14,9 +14,9 @@
       <Sha>5ce78f66d89ea529e459abddb129ab36cb5bd936</Sha>
       <SourceBuild RepoName="diagnostics" ManagedOnly="true" />
     </Dependency>
-    <Dependency Name="Microsoft.SourceBuild.Intermediate.source-build-externals" Version="8.0.0-alpha.1.23262.1">
+    <Dependency Name="Microsoft.SourceBuild.Intermediate.source-build-externals" Version="8.0.0-alpha.1.23268.1">
       <Uri>https://github.com/dotnet/source-build-externals</Uri>
-      <Sha>a1460948fd0a4ab66b885c1575b085af70139e9a</Sha>
+      <Sha>21d564f9e16f7986d8af0692258afb91a52dda80</Sha>
       <SourceBuild RepoName="source-build-externals" ManagedOnly="true" />
     </Dependency>
     <Dependency Name="Microsoft.SourceBuild.Intermediate.source-build-reference-packages" Version="8.0.0-alpha.1.23272.1">