gstgiosrc: Don't leak scheme string in gst_gio_src_query()

Add a g_free() in the code path that forwards the query to the parent
handler.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/1078>

gst/gio/gstgiosrc.c

@@ -485,6 +485,7 @@ gst_gio_src_query (GstBaseSrc * base_src, GstQuery * query)
             "no random access possible", scheme);
       } else {
         GST_LOG_OBJECT (src, "unhandled protocol '%s', asking parent", scheme);
+        g_free (scheme);
         goto forward_parent;
       }
       g_free (scheme);