Bigger combo index (#9318)

* Add change log

* Change combo index from uint8_t to uint16_t

quantum/process_keycode/process_combo.h

@@ -56,7 +56,7 @@ typedef struct {
 
 bool process_combo(uint16_t keycode, keyrecord_t *record);
 void matrix_scan_combo(void);
-void process_combo_event(uint8_t combo_index, bool pressed);
+void process_combo_event(uint16_t combo_index, bool pressed);
 
 void combo_enable(void);
 void combo_disable(void);