Implementation of SHA-256 using Python (#5532)

* Add files via upload

* Update sha256.py

* Update sha256.py

* Update sha256.py

* Update sha256.py

* Update sha256.py

* Update sha256.py

* Update sha256.py

* Update sha256.py

* @staticmethod def preprocessing(data: bytes) -> bytes:

Co-authored-by: Christian Clauss <cclauss@me.com>