include packing in points_frag.glsl to fix compile error (#9355)

src/renderers/shaders/ShaderLib/points_frag.glsl

@@ -2,6 +2,7 @@ uniform vec3 diffuse;
 uniform float opacity;
 
 #include <common>
+#include <packing>
 #include <color_pars_fragment>
 #include <map_particle_pars_fragment>
 #include <fog_pars_fragment>