Fix -Wincompatible-pointer-types error with gcc 14.

```
[ 50%] Building C object CMakeFiles/jsonmenu.dir/src/jsonmenu.c.o
/home/buildozer/aports/testing/rofi-json-menu/src/rofi-json-menu-0.2.0/src/jsonmenu.c:313:27: error: initialization of 'cairo_surface_t * (*)(const Mode *, unsigned int,  unsigned int)' {aka 'struct _cairo_surface * (*)(const struct rofi_mode *, unsigned int,  unsigned int)'} from incompatible pointer type 'cairo_surface_t * (*)(const Mode *, unsigned int,  int)' {aka 'struct _cairo_surface * (*)(const struct rofi_mode *, unsigned int,  int)'} [-Wincompatible-pointer-types]
  313 |     ._get_icon          = json_menu_get_icon,
      |                           ^~~~~~~~~~~~~~~~~~
/home/buildozer/aports/testing/rofi-json-menu/src/rofi-json-menu-0.2.0/src/jsonmenu.c:313:27: note: (near initialization for 'mode._get_icon')
```

--- rofi-json-menu-0.2.0-origin/src/jsonmenu.c
+++ rofi-json-menu-0.2.0/src/jsonmenu.c
@@ -222,7 +222,7 @@
     return entry->name;
 }
 
-static cairo_surface_t* json_menu_get_icon ( const Mode* sw, unsigned int selected_line, int height )
+static cairo_surface_t* json_menu_get_icon ( const Mode* sw, unsigned int selected_line, unsigned int height )
 {
     JsonMenuModePrivateData* pd = ( JsonMenuModePrivateData * ) mode_get_private_data ( sw );
     Entry *entry = &pd->entries[selected_line];