Prepare to update picocalc_keyboard to v1.6 made by @ernst

This version has the following changes:

* return the bios version with REG_ID_VER
* Improved backlight setting for LCD and Keyboard
* Replaced delay() with a non-blocking delay nbDelay()
* Implements monitoring of receive and request events
* I2C reset if no events were recorded in previous 2.5 seconds indicating a possible I2C malfunction.

Code/picocalc_keyboard/keyboard.ino

@@ -176,7 +176,7 @@ static void transition_to(struct list_item * const p_item, const enum key_state
                 lcd_backlight_update(LCD_BACKLIGHT_STEP);
               }else if(chr == ' '){
                 //loop update keyboard backlight
-                kbd_backlight_update_offset();
+                kbd_backlight_update(KBD_BACKLIGHT_STEP);
               }else if(chr == 'B'){
                 show_bat_segs();
               }