Update Debian references (#15297)

Author: richlander

tests/UnitTests.proj

@@ -61,7 +61,7 @@
   <ItemGroup Condition=" '$(HelixAccessToken)' != '' ">
     <HelixTargetQueue Include="(AlmaLinux.8.Amd64)[email protected]/dotnet-buildtools/prereqs:almalinux-8-helix-amd64"/>
     <HelixTargetQueue Include="Windows.10.Amd64"/>
-    <HelixTargetQueue Include="(Debian.11.Amd64)[email protected]/dotnet-buildtools/prereqs:debian-11-helix-amd64"/>
+    <HelixTargetQueue Include="(Debian.12.Amd64)[email protected]/dotnet-buildtools/prereqs:debian-12-helix-amd64"/>
   </ItemGroup>
 
   <PropertyGroup Condition=" '$(HelixAccessToken)' == '' ">
@@ -73,7 +73,7 @@
   <ItemGroup Condition=" '$(HelixAccessToken)' == '' ">
     <HelixTargetQueue Include="(AlmaLinux.8.Amd64.Open)[email protected]/dotnet-buildtools/prereqs:almalinux-8-helix-amd64"/>
     <HelixTargetQueue Include="Windows.10.Amd64.Open"/>
-    <HelixTargetQueue Include="(Debian.11.Amd64.Open)[email protected]/dotnet-buildtools/prereqs:debian-11-helix-amd64"/>
+    <HelixTargetQueue Include="(Debian.12.Amd64.Open)[email protected]/dotnet-buildtools/prereqs:debian-12-helix-amd64"/>
   </ItemGroup>
 
   <PropertyGroup Condition="!$(HelixTargetQueue.StartsWith('Windows'))">