playback/player: gtk-play: Fix compiler warning

playback/player: gtk-play: Fix compiler warning

gtk-play.c:269:60: warning: passing 'gint *' (aka 'int *') to parameter of type 'guint *' (aka 'unsigned int *') converts between pointers to integer types
      with different sign [-Wpointer-sign]
      gst_player_video_info_get_pixel_aspect_ratio (video, &par_n, &par_d);
                                                           ^~~~~~
../lib/gst/player/gstplayer-media-info.h:92:57: note: passing argument to parameter 'par_n' here
                (const GstPlayerVideoInfo* info, guint *par_n, guint *par_d);
                                                        ^
gtk-play.c:269:68: warning: passing 'gint *' (aka 'int *') to parameter of type 'guint *' (aka 'unsigned int *') converts between pointers to integer types
      with different sign [-Wpointer-sign]
      gst_player_video_info_get_pixel_aspect_ratio (video, &par_n, &par_d);
                                                                   ^~~~~~
../lib/gst/player/gstplayer-media-info.h:92:71: note: passing argument to parameter 'par_d' here
                (const GstPlayerVideoInfo* info, guint *par_n, guint *par_d);
                                                                      ^