Prepare for v1.0.3 🔱

[RobertoPrevato]

• Add a roles property to the Identity object.
• Add a RolesRequirement class to authorize by sufficient roles (any one is enough).
• Add support for validating JWTs signed using symmetric encryption (SymmetricJWTValidator and AsymmetricJWTValidator).
• Add support to call the authorize method with an optional set of roles, treated as sufficient roles to succeed authorization.
• Add Python 3.12 and 3.13 to the build matrix. Remove Python 3.8 from the build matrix.
• Improve pyproject.toml.