Initial pass at support for 10.9.1

[jesseward]

Summary

This introduces compatibility with 10.9.x Jellyfin versions

• Support for JF 10.9.1 (https://github.com/jesseward/jellyfin-plugin-lastfm/issues/63)
• Tag plugin version 8.1.0.0
• Bump to dot net 8.0
• Swap the ServerEntryPoint interface from IServerEntryPoint to IHostedService
• ingest mcr.microsoft.com/devcontainers/dotnet:8.0" as the devcontainer
• Fix for scrobble model (bool becomes int) - https://github.com/jesseward/jellyfin-plugin-lastfm/issues/59