This update for gstreamer-editing-services, gstreamer-plugins-libav, gstreamer-plugins-vaapi, python-gst fixes the following issues:

gstreamer-plugins-libav was update to version 1.16.3 (boo#1181255):

- avaudenc/avvidenc: Reopen encoding session if it's required
- avauddec/audenc/videnc: Don't return GST_FLOW_EOS when draining
- avauddec/avviddec: Avoid dropping non-OK flow return
- avviddec: Limit default number of decoder threads
- avauddec: fix buffer leak when send packet failed
- Ensure drain even if codec has not delay capabilities

gstreamer-plugins-vaapi was updated to version 1.16.3 (boo#1181255):

- display: drm: use g_strcmp0 to be null safe
- vaapipluginutil: Use `GST_VAAPI_DISPLAY_TYPE_DRM` for Mesa3D GBM
- vaapivideobufferpool: force video meta if sizes are different
- Fix negotiate lock
- decoder: h265: parser state after update dependent slice
- h265enc: Set `VA_PICTURE_HEVC_INVALID` flag for invalid picture
- vaapivideobufferpool: Log messages in proper category.
- vaapih264enc: fix log message
- display: fix a resource leak in X11 pixmap format.
- decoder: h264, h265: `fix g_return_val_if_fail()` missuse
- utils: guard the VAEntrypointFEI symbol
- h265dec: remove limitation of get iq matrix
- videopool: fix undocumented behavior and counting
- Remove last negotiated video info if caps are the same
- encoder: increase bitrate prop max value
- misc backports into 1.16

gstreamer-editing-services was updated to version 1.16.3 (boo#1181255):

+ ges-launch fixes: enhance error message when no clip duration
  is set, avoid setting invalid clip duration

python-gst was updated to version 1.16.3 (boo#1181255):

+ Add exampleTransform.py from the master branch,
  modified to work on 1.16
+ Fix build with Python 3.8 by also checking for
  python-3.X-embed.pc