Fix T97974: Marker line affected by NLA strip mute

Fix T97974 by having the marker rendering code explicitly set the
required line width.

Reviewed By: sybren

Differential Revision: https://developer.blender.org/D14890

source/blender/editors/animation/anim_markers.c

@@ -543,6 +543,9 @@ void ED_markers_draw(const bContext *C, int flag)
   View2D *v2d = UI_view2d_fromcontext(C);
   int cfra = CTX_data_scene(C)->r.cfra;
 
+  const float line_width = GPU_line_width_get();
+  GPU_line_width(1.0f);
+
   rctf markers_region_rect;
   get_marker_region_rect(v2d, &markers_region_rect);
 
@@ -575,6 +578,7 @@ void ED_markers_draw(const bContext *C, int flag)
     }
   }
 
+  GPU_line_width(line_width);
   GPU_matrix_pop();
 }