Signals are not inherited

All necessary models should be added to signals directly. Sometimes it is not comfortably because we must remember about this point and can't use the standard habitual OOP logic.
Example for reproducing:

from tortoise import fields, Model
from typing import Any

class Base(Model):
    id = fields.IntField(pk=True)

    class Meta:
        abstract = True


@pre_save(Base)
async def signal_pre_save(*args: Any, **kwargs: Any) -> None:
    print("Base pre_save. And it will be executed nowhere")

class Foo(Base):
      pass

I've explored and detected a reason of this behavior. Who can sort out with this logic? I guess it was made specially.

I fixed this "issue" by the following workaround (maybe it will be useful for someone):

from tortoise import fields, Model
from tortoise.signals import Signals
from tortoise.signals import pre_save


class CustomListener(dict):

    def get(self, cls: Type, default=None):
        """Tries to look for signals with MRO logic
        """
        listeners = super().get(cls, default)
        if not listeners:
            for parent_cls in cls.__bases__:
                listeners = self.get(parent_cls, default=default)
                if listeners:
                    return listeners
        return []


class Base(Model):
    _listeners: Dict[Signals, CustomListener] = {  # type: ignore
        Signals.pre_save: CustomListener(),
        Signals.post_save: CustomListener(),
        Signals.pre_delete: CustomListener(),
        Signals.post_delete: CustomListener(),
    }

    class Meta:
        abstract = True

@pre_save(Base)
async def signal_pre_save(*args: Any, **kwargs: Any) -> None:
        print("Base pre_save. And it will be executed for all children")

class Foo(Base):
      pass

Start with the signal registration and model logic referenced in tortoise/models.py around line 838, then trace how listeners are selected for subclasses. Reproduce the Base/Foo example and compare the behavior with the proposed MRO-style workaround; done means the intended inheritance behavior is established and covered by a regression test.