Fix Python 3.13: classmethod + property unsupported (#448)

* Use own classproperty (don't inherit from property).
 * Config generation: Rename pathlib._local to pathlib

src/akkudoktoreos/core/decorators.py

@@ -1,3 +1,4 @@
+from collections.abc import Callable
 from typing import Any, Optional
 
 from akkudoktoreos.core.logging import get_logger
@@ -5,13 +6,14 @@ from akkudoktoreos.core.logging import get_logger
 logger = get_logger(__name__)
 
 
-class classproperty(property):
+class classproperty:
     """A decorator to define a read-only property at the class level.
 
-    This class extends the built-in `property` to allow a method to be accessed
-    as a property on the class itself, rather than an instance. This is useful
-    when you want a property-like syntax for methods that depend on the class
-    rather than any instance of the class.
+    This class replaces the built-in `property` which is no longer available in
+    combination with @classmethod since Python 3.13 to allow a method to be
+    accessed as a property on the class itself, rather than an instance. This
+    is useful when you want a property-like syntax for methods that depend on
+    the class rather than any instance of the class.
 
     Example:
         class MyClass:
@@ -28,13 +30,16 @@ class classproperty(property):
                  decorated method on the class.
 
     Parameters:
-        fget (Callable[[type], Any]): A method that takes the class as an
+        fget (Callable[[Any], Any]): A method that takes the class as an
                                       argument and returns a value.
 
     Raises:
         AssertionError: If `fget` is not defined when `__get__` is called.
     """
 
+    def __init__(self, fget: Callable[[Any], Any]) -> None:
+        self.fget = fget
+
     def __get__(self, _: Any, owner_cls: Optional[type[Any]] = None) -> Any:
         if owner_cls is None:
             return self