fix: ensure config directory exists when creating config file

If the config file directory doesn't already exist, the application will
crash on startup while trying to create the default configuration. Fix
this by creating the directory.

Drive-by: Replace os.path functions by pathlib's functions

application/util/config.py

@@ -1,5 +1,3 @@
-import os
-
 from pydantic import BaseModel
 from yaml import dump, safe_load
 
@@ -39,13 +37,14 @@ def create_default_config():
             "toggle-scroll": "s",
         },
     }
-    with open(CONFIG_PATH, "w") as file:
+    CONFIG_PATH.parent.mkdir(parents=True, exist_ok=True)
+    with CONFIG_PATH.open("w") as file:
         dump(default_config, file)
 
 
 def load_config():
-    if not os.path.exists(CONFIG_PATH):
+    if not CONFIG_PATH.exists():
         create_default_config()
-    with open(CONFIG_PATH, "r") as file:
+    with CONFIG_PATH.open() as file:
         config_dict = safe_load(file)
         return Config(**config_dict)