CasaOS-UserService allows unauthorized access to any file

CasaOS-UserService provides user management functionalities to CasaOS. Prior to version 0.4.7, path filtering of the URL for user avatar image files was not strict, making it possible to get any file on the system. This could allow an unauthorized actor to access, for example, the CasaOS user database, and possibly obtain system root privileges. Version 0.4.7 fixes this issue.