Fix T57111: Particle texture keyframes missing from Graph Editor

The entire particle system was skipped when the particle system itself did
not have any animation data. This caused the animation data on the texture
to be skipped.

source/blender/editors/animation/anim_filter.c

@@ -2433,8 +2433,9 @@ static size_t animdata_filter_ds_particles(
     ListBase tmp_data = {NULL, NULL};
     size_t tmp_items = 0;
 
-    /* if no material returned, skip - so that we don't get weird blank entries... */
-    if (ELEM(NULL, psys->part, psys->part->adt)) {
+    /* Note that when psys->part->adt is NULL the textures can still be
+     * animated. */
+    if (psys->part == NULL) {
       continue;
     }