feat: check if @property overrides parent class variable

Author: shenyih0ng

mypy/checker.py

@@ -2280,6 +2280,17 @@ def check_method_override_for_base_with_name(
             if inner is not None:
                 typ = inner
                 typ = get_property_type(typ)
+
+                if (
+                    isinstance(original_node, Var)
+                    and original_node.is_classvar
+                    and defn.name == original_node.name
+                    and isinstance(defn, Decorator)
+                ):
+                    self.fail(
+                        message_registry.CANNOT_OVERRIDE_CLASS_VAR.format(base.name), defn.func
+                    )
+
                 if (
                     isinstance(original_node, Var)
                     and not original_node.is_final