Fix critical gstreamer error

[frostbyte73]

Error when removing a source bin:

(egress:93): GStreamer-WARNING **: 22:05:15.736:
Trying to join task 0xffff38173bc0 from its thread would deadlock.
You cannot change the state of an element from its streaming
thread. Use g_idle_add() or post a GstMessage on the bus to
schedule the state change from the main thread.

(egress:93): GStreamer-CRITICAL **: 22:05:15.741: Failed to deactivate pad video_input_queue:src, very bad