[BUG] Unexpected \0 after decrypted filenames in manifest

[oureveryday]

Description
steam/core/manifest.py
Unexpected \0 after decrypted filenames in manifest

When I uses manifest saved by ValvePython in depotdownloader, a exception was raised. Upon checking, I found that there are a additional \0 in filename, which causes the problem.

[oureveryday]

Also there is no crc recalculation when serilalizing manifest file.