Update pickle_storage.py

[thebocher]

fixed typo in StatePickleStorage.save, which didn't allow to save user state, but instead copied the whole content of state file inside "data"

Description

Include changes, new features and etc:
fixed typo

Describe your tests

How did you test your change?
my one year old bot started working again

Python version: any

OS: any

Checklist:

• [ no ] I added/edited example on new feature/change (if exists)
• [ yes ] My changes won't break backward compatibility
• [ no ] I made changes both for sync and async

[Badiboy]

Looks correct. @coder2020official ?

[coder2020official]

Thanks