fix: playback of malformed MP4 files with invalid framerates

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Some malformed MP4 files previously wouldn't play at all because they
reported a 0/1 framerate.
Other files suffered from severe audio stuttering caused by repeated
long GAP events emitted from malformed edit lists.
This patch treats invalid framerates as unknown (allowing the existing
fallback to be used) and suppresses suspicious long audio GAP events
before they reach the audio sink.
As a result, both kinds of videos now play correctly.

Cargo.lock

@@ -2808,7 +2808,7 @@ dependencies = [
 [[package]]
 name = "iced_video_player"
 version = "0.6.0"
-source = "git+https://github.com/wash2/iced_video_player.git?branch=iced-rebase#cb3635192f3dec37619855c904a168ca37a3dac3"
+source = "git+https://github.com/wash2/iced_video_player.git?branch=iced-rebase#2e82b6b08d1751924b7b21b8c56683cdbc57bc33"
 dependencies = [
  "glib",
  "gstreamer",