Custom shift keys: call send_keyboard_report().

#5
reports that the shift mod is not correctly cleared, e.g. for the custom
shift key `{KC_COMM, KC_SCLN}`, a `:` is typed instead of `;`. To test a
plausible fix, this commit adds a `send_keyboard_report()` call between
removing the shift mods and registering the keycode.

features/custom_shift_keys.c

@@ -42,6 +42,7 @@ bool process_custom_shift_keys(uint16_t keycode, keyrecord_t *record) {
 #endif  // NO_ACTION_ONESHOT
           del_mods(MOD_MASK_SHIFT);
           del_weak_mods(MOD_MASK_SHIFT);
+          send_keyboard_report();
           registered_keycode = custom_shift_keys[i].shifted_keycode;
         } else {
           registered_keycode = custom_shift_keys[i].keycode;