Various fixes

[BlueRaja]

• Updating SteamAuth, SteamKit, and Json.net versions
  • (not using the latest SteamKit because there was a major version bump! We should update for that)
• Fix bug causing trade offer confirmations to break
• Fix bug causing bot to crash when loading some inventories
• Make Bot._loadTask public so bots can wait until load is complete

Sorry I didn't pull these into separate PR's 😅 also sorry for being too lazy to rebase, so there's lots of old empty merge commits