Modes not working -> Extend unit test

Hy dear LifeHash developers,

nice project. Yet, using you code with python 3.13 sadly made some issues.
It seems you are expecting to have the "+" operator to be defined on a hashlib.sha256 as well as hashlib.sha256 on another hashlib.sha256 ( sha256(sha256(bytes)) ).
lifehash/lifehash.py line 1024 thus fails. I think you just need to add a few .digest() here and there.

I get why you did not see that. I strongly suggest to extend you unit tests to test *all* modes for you LifeHash. Currently you only test version2.