* Update callback_data.py
Allows using a default value in the class which is equal to an empty string ("").
Example:
class MyCallbackData(CallbackData, prefix="MyCallbackData"):
input1: str
input2: str = ""
* Create 1493.bugfix.rst
* Update callback_data.py
Fixed an issue that prevented unpacking None values.
* Added tests for CallbackData
* Update tests/test_filters/test_callback_data.py
Co-authored-by: Oleg A. <t0rr@mail.ru>
* Update test_callback_data.py
* Update callback_data.py
* Update 1493.bugfix.rst
---------
Co-authored-by: Oleg A. <t0rr@mail.ru>
