fix(ugo): import the PPM module explicitly

Resolve the module instead of its exported class so embedded-thumbnail decoding works.

Hatenatools/UGO.py

@@ -8,11 +8,12 @@ from __future__ import annotations
 
 import os
 import sys
+from importlib import import_module
 from base64 import b64decode, b64encode
 import xml.etree.ElementTree as ET
 
 try:
-    from . import PPM as _ppm_module
+    _ppm_module = import_module(".PPM", __package__)
     HasPPM = True
 except (ImportError, ValueError):
     try: