Schedule removal for deprecated `abc` decorators

[aiwonderland]

Proposal:

Remove deprecated abc.abstractclassmethod, abc.abstractstaticmethod and abc.abstractproperty for 3.16.
or maybe and an warn:

import warnings
# codes ...
class abstractproperty(property):
    __isabstractmethod__ = True

    def __init__(self, fget=None, fset=None, fdel=None, doc=None):
        warnings.warn(
            "abc.abstractproperty is deprecated and will be removed in Python 3.16. "
            "Use @property with @abstractmethod instead.",
            FutureWarning,
            stacklevel=2
        )
        super().__init__(fget, fset, fdel, doc)

[picnixz]

I really want those methods to be gone. It's annoying that they are sometimes suggested by my IDE!

[picnixz]

Oh wait, there was no warning? so no we can't remove them sorry.

[picnixz]

They've been deprecated since 3.3. If we plan to deprecate them (warning+removal) we need a 5y period first now.

[picnixz]

cc @JelleZijlstra @sobolevn @hugovk @rhettinger

[aiwonderland]

thanks 👍