Update Microsoft.AspNetCore.Mvc.Testing requirement from 2.1.* to 8.0.*

Updates the requirements on [Microsoft.AspNetCore.Mvc.Testing](https://github.com/dotnet/aspnetcore) to permit the latest version.
- [Release notes](https://github.com/dotnet/aspnetcore/releases)
- [Changelog](https://github.com/dotnet/aspnetcore/blob/main/docs/ReleasePlanning.md)
- [Commits](https://github.com/dotnet/aspnetcore/commits/v8.0.0)

---
updated-dependencies:
- dependency-name: Microsoft.AspNetCore.Mvc.Testing
  dependency-type: direct:production
...

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

Tests.props

@@ -19,11 +19,11 @@
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3" Condition="'$(TargetFramework)' == 'netcoreapp2.1'" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5" Condition="'$(TargetFramework)' != 'netcoreapp2.1'" />
     <PackageReference Include="Moq" Version="4.20.69" />
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="2.1.*" Condition="'$(TargetFramework)' == 'netcoreapp2.1' OR '$(TargetFramework)' == 'net48'" />
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="3.1.*" Condition="'$(TargetFramework)' == 'netcoreapp3.1'" />
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="5.0.*" Condition="'$(TargetFramework)' == 'net5.0'" />
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="6.0.*" Condition="'$(TargetFramework)' == 'net6.0'" />
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="7.0.*" Condition="'$(TargetFramework)' == 'net7.0'" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="8.0.*" Condition="'$(TargetFramework)' == 'netcoreapp2.1' OR '$(TargetFramework)' == 'net48'" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="8.0.*" Condition="'$(TargetFramework)' == 'netcoreapp3.1'" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="8.0.*" Condition="'$(TargetFramework)' == 'net5.0'" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="8.0.*" Condition="'$(TargetFramework)' == 'net6.0'" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="8.0.*" Condition="'$(TargetFramework)' == 'net7.0'" />
     <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="2.1.*" Condition="'$(TargetFramework)' == 'netcoreapp2.1' OR '$(TargetFramework)' == 'net48'" />
     <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="3.1.*" Condition="'$(TargetFramework)' == 'netcoreapp3.1'" />
     <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="5.0.*" Condition="'$(TargetFramework)' == 'net5.0'" />