GHSA-8qvf-mr4w-9x2c: Mesop has a Path Traversal utilizing `FileStateSessionBackend` leads to Application Denial of Service and File Write/Deletion

Mesop has a path traversal vulnerability (a technique where an attacker uses sequences like `../` to escape intended directory boundaries) in its file-based session backend that allows attackers to read, write, or delete arbitrary files on the server by crafting malicious `state_token` values in messages sent to the `/ui` endpoint. This can crash the application or give attackers unauthorized access to system files.