Use sys._clear_type_descriptors() on 3.14 to break slot reference cycle (#1459)

* Use sys._clear_type_descriptors() on 3.14

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* No more deproxying

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: JelleZijlstra

src/attr/_make.py

@@ -24,7 +24,6 @@
     PY_3_10_PLUS,
     PY_3_11_PLUS,
     PY_3_13_PLUS,
-    PY_3_14_PLUS,
     _AnnotationExtractor,
     _get_annotations,
     get_generic_base,
@@ -629,17 +628,6 @@ def evolve(*args, **changes):
     return cls(**changes)
 
 
-# Hack to the get the underlying dict out of a mappingproxy
-# Use it with: cls.__dict__ | _deproxier
-# See: https://github.com/python/cpython/pull/136893
-class _Deproxier:
-    def __ror__(self, other):
-        return other
-
-
-_deproxier = _Deproxier()
-
-
 class _ClassBuilder:
     """
     Iteratively build *one* class.
@@ -869,19 +857,9 @@ def _create_slots_class(self):
             if k not in (*tuple(self._attr_names), "__dict__", "__weakref__")
         }
 
-        if PY_3_14_PLUS:
-            # Clean up old dict to avoid leaks.
-            old_cls_dict = self._cls.__dict__ | _deproxier
-            old_cls_dict.pop("__dict__", None)
-            if "__weakref__" in self._cls.__dict__:
-                del self._cls.__weakref__
-
-            # Manually bump internal version tag.
-            try:
-                self._cls.__abstractmethods__ = self._cls.__abstractmethods__
-            except AttributeError:
-                self._cls.__abstractmethods__ = frozenset({"__init__"})
-                del self._cls.__abstractmethods__
+        # 3.14.0rc2+
+        if hasattr(sys, "_clear_type_descriptors"):
+            sys._clear_type_descriptors(self._cls)
 
         # If our class doesn't have its own implementation of __setattr__
         # (either from the user or by us), check the bases, if one of them has