Add github.com/Eyevinn/mp4ff repo (#5482)

* Add github.com/Eyevinn/mp4ff repo

* Remove https://github.com/ziutek/gst since unmaintained and lacking go.mod

* Remove github.com/wargarblgarbl/libgosubs since unmaintained and lacking go.mod

README.md

@@ -2993,10 +2993,9 @@ _Libraries for manipulating video._
 - [go-mpd](https://github.com/unki2aut/go-mpd) - Parser and generator library for MPEG-DASH manifest files.
 - [goav](https://github.com/giorgisio/goav) - Comprehensive Go bindings for FFmpeg.
 - [gortsplib](https://github.com/aler9/gortsplib) - Pure Go RTSP server and client library.
-- [gst](https://github.com/ziutek/gst) - Go bindings for GStreamer.
-- [libgosubs](https://github.com/wargarblgarbl/libgosubs) - Subtitle format support for go. Supports .srt, .ttml, and .ass.
 - [libvlc-go](https://github.com/adrg/libvlc-go) - Go bindings for libvlc 2.X/3.X/4.X (used by the VLC media player).
 - [m3u8](https://github.com/grafov/m3u8) - Parser and generator library of M3U8 playlists for Apple HLS.
+- [mp4ff](https://github.com/Eyevinn/mp4ff) - Library and tools for working with MP4 files containing video, audio, subtitles, or metadata.
 - [v4l](https://github.com/korandiz/v4l) - Video capture library for Linux, written in Go.
 
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