Make parent directories when needed

lib/youseedee/__init__.py

@@ -39,7 +39,7 @@ def bisect_key(haystack, needle, key):
 def ucd_dir():
     """Return the directory where Unicode data is stored"""
     ucddir = Path(platformdirs.user_cache_dir("youseedee"))
-    ucddir.mkdir(exist_ok=True)
+    ucddir.mkdir(exist_ok=True, parents=True)
     return ucddir