fix(picker): add fallback for skintone_id

[actionless]

Fixes:

Traceback (most recent call last):
  File "/usr/lib/python3.10/site-packages/emote/__init__.py", line 72, in handle_accelerator
    self.create_picker_window()
  File "/usr/lib/python3.10/site-packages/emote/__init__.py", line 87, in create_picker_window
    self.picker_window = picker.EmojiPicker(
  File "/usr/lib/python3.10/site-packages/emote/picker.py", line 46, in __init__
    self.init_header()
  File "/usr/lib/python3.10/site-packages/emote/picker.py", line 77, in init_header
    header.pack_end(self.init_skintone_button())
  File "/usr/lib/python3.10/site-packages/emote/picker.py", line 135, in init_skintone_button
    skintone_combo.set_active(user_data.SKINTONES.index(user_data.load_skintone()))
ValueError: '🟨' is not in list