Granian: DoS via WSGI response header panic

Granian is a Rust HTTP server for Python applications. From 0.2.0 to 2.7.4, Granian aborts a worker process if a WSGI application returns an invalid HTTP response header name or value. The WSGI response conversion path uses .unwrap() on both the header name and header value constructors, so malformed output from the application becomes a process abort instead of a handled error. This vulnerability is fixed in 2.7.4.