Emmett has a path traversal in internal assets handler

Emmett is a full-stack Python web framework designed with simplicity. From 2.5.0 to before 2.8.1, the RSGI static handler for Emmett's internal assets (/__emmett__ paths) is vulnerable to path traversal attacks. An attacker can use ../ sequences (eg /__emmett__/../rsgi/handlers.py) to read arbitrary files outside the assets directory. This vulnerability is fixed in 2.8.1.