How to update the bindings

Take the updated .gir files (e.g. from your gst-build checkout) and put them in the gir-files directory
In the gir-files directory, run ./fix.sh
In the GstVideo-1.0.gir file, the GST_VIDEO_BUFFER_FLAG_ONEFIELD and GST_VIDEO_FRAME_FLAG_ONEFIELD flags are twice. This is a gir bug. Delete the second one.
If there is a new GStreamer version: Manually update gst*/Cargo.toml and gst*/build.rs files. generator.py will mess these up.
Run generator.py
git checkout gst*/Cargo.toml gst*/build.rs
Investigate the diff and fix any mess-ups