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] <support@github.com>

Author: dependabot[bot]

GlobalMute.csproj

@@ -50,7 +50,7 @@
     </Compile>
   </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.ILLink.Tasks" Version="8.0.20" />
+    <PackageReference Include="Microsoft.NET.ILLink.Tasks" Version="8.0.21" />
     <EmbeddedResource Update="Properties\Resources.resx">
       <Generator>ResXFileCodeGenerator</Generator>
       <LastGenOutput>Resources.Designer.cs</LastGenOutput>