multimedia/elementary-videos: update to 3.0.0

ChangeLog: https://github.com/elementary/videos/releases/tag/3.0.0

• Use playbin with the gst gtk widget for playback
• Separate headerbars with deck pages
• PlaylistItem: Some gtk4 preparations
• Playlist: Preparations for GTK4
• PlaylistPopover: send app notification when adding
• LibraryItem: Simplifications and preparations for GTK4
• LibraryPage: Preparations for GTK4
• EpisodesPage: Preparations for GTK4
• README: build with Flatpak
• BottomBar and PlayerPage: GTK4 preparations
• SettingsPopover: Preparations for GTK4
• Window: put everything in a windowhandle
• PlaybackManager: Improve position querying
• Window: Some GTK4 preparations
• PreviewPopover: Preparations for GTK4
• Remove unused Clutter
• Meson: use gnome.post_install to compile schemas
• Metainfo: 3.0.0 release notes
• Update screenshots
• Meson: update to 3.0.0

PR: 273075
Reported by: duchateau.olivier@gmail.com
Reviewed by: