Bump System.Text.Encoding.CodePages from 4.7.1 to 5.0.0

Bumps [System.Text.Encoding.CodePages](https://github.com/dotnet/runtime) from 4.7.1 to 5.0.0.
- [Release notes](https://github.com/dotnet/runtime/releases)
- [Commits](https://github.com/dotnet/runtime/commits)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

test/HtmlSanitizer.Tests/HtmlSanitizer.Tests.csproj

@@ -46,7 +46,7 @@
     </PackageReference>
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="System.Text.Encoding.CodePages">
-      <Version>4.7.1</Version>
+      <Version>5.0.0</Version>
     </PackageReference>
   </ItemGroup>