fix: add support init fields from parent object in KeyboardButton

[Birdi7]

Description

Fixes #343

The KeyboardButton object couldn't be deserialized because of no support of conf parameter(which is inherited from TelegramObject) in __init__ method

Code snippet which produces the error:

from aiogram.types import ReplyKeyboardMarkup, KeyboardButton

markup = ReplyKeyboardMarkup(row_width=4, resize_keyboard=True)
markup.add(KeyboardButton('something here'))
dict_kb = markup.to_python()
assert ReplyKeyboardMarkup.to_object(dict_kb) == markup

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

I ran code snippet, which I included above. In addition, I added several unit tests to verify this behavior.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes