metadata: Enable UTF-8 support in metadata scanner
GStreamer's gst_init() hasn't done that for us since 2012: https://gitlab.freedesktop.org/gstreamer/gstreamer/commit/9326124581e65c7f4dc6a729f12c1dca77d564f3
GStreamer's gst_init() hasn't done that for us since 2012: https://gitlab.freedesktop.org/gstreamer/gstreamer/commit/9326124581e65c7f4dc6a729f12c1dca77d564f3