Bump Microsoft.NET.ILLink.Tasks from 8.0.20 to 8.0.21

---
updated-dependencies:
- dependency-name: Microsoft.NET.ILLink.Tasks
  dependency-version: 8.0.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

src/OpenOnlineConfig/OpenOnlineConfig/OpenOnlineConfig.csproj

@@ -20,7 +20,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.ILLink.Tasks" Version="8.0.20" />
+    <PackageReference Include="Microsoft.NET.ILLink.Tasks" Version="8.0.21" />
     <None Include="..\..\..\LICENSE">
       <Pack>True</Pack>
       <PackagePath></PackagePath>