Convert Encoder callbacks to be boolean functions (#12805)

Co-authored-by: James Young <[email protected]>

keyboards/nullbitsco/nibble/keymaps/oled/keymap.c

@@ -122,12 +122,13 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
 }
 
 
-void encoder_update_user(uint8_t index, bool clockwise) {
+bool encoder_update_user(uint8_t index, bool clockwise) {
     if (clockwise) {
         tap_code(KC_VOLU);
     } else {
         tap_code(KC_VOLD);
     }
+    return true;
 }
 
 void matrix_init_user(void) {