[tracker-miners/sam/const-warning-fix] tracker-extract-gstreamer.c: Fix 'const' warning

[Sam Thursfield <sthursfield src gnome org>]

commit c8f60591070a7a0dc98df08b7933afd61de77762
Author: Sam Thursfield <sam thursfield codethink co uk>
Date:   Mon Oct 3 13:10:08 2022 +0200

    tracker-extract-gstreamer.c: Fix 'const' warning
    
    gst_discoverer_stream_info_get_tags() now returns a
    `const GstTagList *`.
    
    No functional changes.

 src/tracker-extract/tracker-extract-gstreamer.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/tracker-extract/tracker-extract-gstreamer.c b/src/tracker-extract/tracker-extract-gstreamer.c
index f0e0861ba..b521962dc 100644
--- a/src/tracker-extract/tracker-extract-gstreamer.c
+++ b/src/tracker-extract/tracker-extract-gstreamer.c
@@ -1293,7 +1293,8 @@ discoverer_init_and_run (MetadataExtractor *extractor,
 
        for (l = extractor->streams; l; l = g_list_next (l)) {
                GstDiscovererStreamInfo *stream = l->data;
-               GstTagList *stream_tags, *copy = NULL;
+               const GstTagList *stream_tags;
+               GstTagList *copy = NULL;
 
                stream_tags = gst_discoverer_stream_info_get_tags (stream);