Bump Duende.IdentityServer in /samples/IdentityServer.ServerSample

Bumps [Duende.IdentityServer](https://github.com/DuendeSoftware/IdentityServer) from 7.0.7 to 7.0.8.
- [Release notes](https://github.com/DuendeSoftware/IdentityServer/releases)
- [Commits](DuendeSoftware/products@7.0.7...7.0.8)

---
updated-dependencies:
- dependency-name: Duende.IdentityServer
  dependency-type: direct:production
...

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

Author: dependabot[bot]

samples/IdentityServer.ServerSample/IdentityServer.ServerSample.csproj

@@ -19,7 +19,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="Duende.IdentityServer" Version="7.0.7" />
+        <PackageReference Include="Duende.IdentityServer" Version="7.0.8" />
         <PackageReference Include="Microsoft.ApplicationInsights.AspNetCore" Version="2.22.0" />
         <PackageReference Include="Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation" Version="8.0.10" />
         <PackageReference Include="Microsoft.Extensions.Logging.ApplicationInsights" Version="2.22.0" />