Update dependency Selenium.Support to v4.21.0

Author: renovate[bot]

examples/dotnet/SeleniumDocs/SeleniumDocs.csproj

@@ -10,7 +10,7 @@
       <PackageReference Include="Microsoft.IdentityModel.Tokens" Version="7.5.2" />
       <PackageReference Include="MSTest.TestAdapter" Version="3.3.1" />
       <PackageReference Include="MSTest.TestFramework" Version="3.3.1" />
-      <PackageReference Include="Selenium.Support" Version="4.20.0" />
+      <PackageReference Include="Selenium.Support" Version="4.21.0" />
       <PackageReference Include="Selenium.WebDriver" Version="4.20.0" />
     </ItemGroup>