Check B105:hardcoded_password_string for class attributes

[yoeran-dev]

Is your feature request related to a problem? Please describe.
Bandit does not throw an error for self.password = "12123123" but does so for password = "12123123"

Describe the solution you'd like
Make it so B105:hardcoded_password_string also checks class attributes

[noliverio]

Hi, I think this makes sense, and it seem like those should be included in the check.

Unless anyone has any objections I'd like to take this and run with it.