Adapt to new serialization of enums

GStreamer 1.18 changed the serialization of enums.

This patch updates to handle the new format.

In absence of that, the script was failing like this:

Traceback (most recent call last):
  File "/home/ntrrgc/Apps/gstreamer/./subprojects/gst-devtools/tracer/", line 224, in <module>
  File "/home/ntrrgc/Apps/gstreamer/subprojects/gst-devtools/tracer/tracer/", line 42, in run
  File "/home/ntrrgc/Apps/gstreamer/subprojects/gst-devtools/tracer/tracer/", line 27, in handle_tracer_entry
  File "/home/ntrrgc/Apps/gstreamer/./subprojects/gst-devtools/tracer/", line 114, in handle_tracer_entry
    key = (_SCOPE_RELATED_TO[sv.values['related-to']] + ":" + str(s.values[sk]))
KeyError: 'thread'

Merge request reports