build(deps): Bump SonarAnalyzer.CSharp from 9.20.0.85982 to 9.21.0.86780 (#1407)

Bumps [SonarAnalyzer.CSharp](https://github.com/SonarSource/sonar-dotnet) from 9.20.0.85982 to 9.21.0.86780.
- [Release notes](https://github.com/SonarSource/sonar-dotnet/releases)
- [Commits](SonarSource/sonar-dotnet@9.20.0.85982...9.21.0.86780)

---
updated-dependencies:
- dependency-name: SonarAnalyzer.CSharp
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Directory.Build.props

@@ -52,7 +52,7 @@
 	<!-- Shared code analyzers used for all projects in the solution -->
 	<ItemGroup Label="Code Analyzers">
 		<PackageReference Include="AsyncFixer" Version="1.6.0" PrivateAssets="All" />
-		<PackageReference Include="SonarAnalyzer.CSharp" Version="9.20.0.85982" PrivateAssets="All" />
+		<PackageReference Include="SonarAnalyzer.CSharp" Version="9.21.0.86780" PrivateAssets="All" />
 	</ItemGroup>
 
 	<ItemGroup Label="Implicit usings"