Unused parameter warning

[highvoltage]

Hi, it looks like builds fail on newer gcc versions due to an unused parameter, build log follows:

make[3]: *** [CMakeFiles/catimg.dir/build.make:82: CMakeFiles/catimg.dir/src/catimg.c.o] Error 1                       
make[3]: *** Waiting for unfinished jobs....                                                              
In file included from /build/catimg-2.8.0/src/sh_color.c:4:                                                             
/build/catimg-2.8.0/src/sh_color.c: In function 'init_hash_colors':                            
/build/catimg-2.8.0/src/sh_color.c:39:60: warning: iteration 246 invokes undefined behavior [-Waggressive-loop-optimizations]
   39 |                 k = kh_put(uint32_t, hash_colors, color_map[i], &ret);                 
      |                                                   ~~~~~~~~~^~~                         
/build/catimg-2.8.0/src/khash.h:464:48: note: in definition of macro 'kh_put'                             
  464 | #define kh_put(name, h, k, r) kh_put_##name(h, k, r)                                              
      |                                                ^                                       
/build/catimg-2.8.0/src/sh_color.c:38:27: note: within this loop                                          
   38 |         for (int i = 0; i < N_COLORS; i++) {                                                      
In file included from /build/catimg-2.8.0/src/sh_image.c:4:                                               
/build/catimg-2.8.0/src/stb_image.h: In function 'stbi__gif_load_next':                                   
/build/catimg-2.8.0/src/stb_image.h:6471:84: warning: unused parameter 'req_comp' [-Wunused-parameter]                  
 6471 | static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, int req_comp, stbi_uc *two_back)
      |                                                                                ~~~~^~~~~~~~                    
/build/catimg-2.8.0/src/stb_image.h: In function 'stbi__gif_load':                                        
/build/catimg-2.8.0/src/stb_image.h:6695:107: warning: unused parameter 'ri' [-Wunused-parameter]                       
 6695 | static void *stbi__gif_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri)
      |                                                                                        ~~~~~~~~~~~~~~~~~~~^~