multimedia/emby-server: Update to 3.2.40.0

Changes this release:

https://github.com/MediaBrowser/Emby/releases/tag/3.2.40.0

Note this is not updated to 3.2.50.0 (latest release) as there is a
runtime bug which causes emby to coredump mono on FreeBSD:

https://github.com/MediaBrowser/Emby/issues/3062