Bump AngleSharp and HtmlSanitizer

Bumps AngleSharp and [HtmlSanitizer](https://github.com/mganss/HtmlSanitizer). These dependencies needed to be updated together.

Updates `AngleSharp` from 0.16.1 to 0.17.1

Updates `HtmlSanitizer` from 6.0.453 to 8.1.870
- [Release notes](https://github.com/mganss/HtmlSanitizer/releases)
- [Commits](mganss/HtmlSanitizer@v6.0.453...v8.1.870)

---
updated-dependencies:
- dependency-name: AngleSharp
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: HtmlSanitizer
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

AdminUI/LearningHub.Nhs.AdminUI/LearningHub.Nhs.AdminUI.csproj

@@ -89,7 +89,7 @@
 		<PackageReference Include="elfhHub.Nhs.Models" Version="3.0.8" />
 		<PackageReference Include="FluentValidation" Version="11.11.0" />
 		<PackageReference Include="FluentValidation.AspNetCore" Version="10.3.4" />
-		<PackageReference Include="HtmlSanitizer" Version="6.0.453" />
+		<PackageReference Include="HtmlSanitizer" Version="8.1.870" />
 		<PackageReference Include="IdentityModel" Version="4.4.0" />
 		<PackageReference Include="LearningHub.Nhs.Caching" Version="2.0.2" />
 		<PackageReference Include="LearningHub.Nhs.Models" Version="3.0.45" />

WebAPI/MigrationTool/LearningHub.Nhs.Migration/LearningHub.Nhs.Migration.csproj

@@ -7,10 +7,10 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="AngleSharp" Version="0.16.1" />
+    <PackageReference Include="AngleSharp" Version="0.17.1" />
     <PackageReference Include="elfhHub.Nhs.Models" Version="3.0.8" />
     <PackageReference Include="FluentValidation" Version="11.11.0" />
-    <PackageReference Include="HtmlSanitizer" Version="6.0.453" />
+    <PackageReference Include="HtmlSanitizer" Version="8.1.870" />
     <PackageReference Include="LearningHub.Nhs.Caching" Version="2.0.0" />
     <PackageReference Include="LearningHub.Nhs.Models" Version="3.0.45" />
 	<PackageReference Update="StyleCop.Analyzers" Version="1.1.118">