Fix optional param for Express 5

Author: acelaya

scripts/serve-pattern-library.js

@@ -17,7 +17,7 @@ export function servePatternLibrary(port = 4001) {
   );
 
   // For any other path, serve the index.html file to allow client-side routing
-  app.get('/:path?', (req, res) => {
+  app.get('/{:path}', (req, res) => {
     res.sendFile(path.join(dirname, '../templates/index.html'));
   });