Remove warnings about pytest asyncio mode

tests/test_dispatcher/test_event/test_event.py

@@ -7,8 +7,6 @@ import pytest
 from aiogram.dispatcher.event.event import EventObserver
 from aiogram.dispatcher.event.handler import HandlerObject
 
-pytestmark = pytest.mark.asyncio
-
 
 async def my_handler(value: str, index: int = 0) -> Any:
     return value

tests/test_dispatcher/test_event/test_handler.py

@@ -11,8 +11,6 @@ from aiogram.handlers import BaseHandler
 from aiogram.types import Update
 from aiogram.utils.warnings import Recommendation
 
-pytestmark = pytest.mark.asyncio
-
 
 def callback1(foo: int, bar: int, baz: int):
     return locals()

tests/test_dispatcher/test_event/test_telegram.py

@@ -12,9 +12,6 @@ from aiogram.dispatcher.router import Router
 from aiogram.filters import Filter
 from aiogram.types import Chat, Message, User
 
-pytestmark = pytest.mark.asyncio
-
-
 # TODO: Test middlewares in routers tree