http_response: fix move assign operator not moving file_info.

Signed-off-by: Luca Schlecker <[email protected]>

include/crow/http_response.h

@@ -87,6 +87,7 @@ namespace crow
             code = r.code;
             headers = std::move(r.headers);
             completed_ = r.completed_;
+            file_info = std::move(r.file_info);
             return *this;
         }