fix: use secure proxy to session cookie

lib/middleware/session.js

@@ -7,7 +7,7 @@ module.exports = function(config) {
         name: 'unleash-session',
         keys: [config.secret],
         maxAge: config.sessionAge,
-        secure: !!config.secureHeaders,
+        secureProxy: !!config.secureHeaders,
         path: config.baseUriPath === '' ? '/' : config.baseUriPath,
     });
 };