Update typescript to 4.9.5

Reviewed By: passy

Differential Revision: D46068908

fbshipit-source-id: 4c1ffff8690eec5a10c67d6c5d1aacf224e0f0d4

desktop/flipper-plugin-core/src/plugin/Plugin.tsx

@@ -202,7 +202,7 @@ export class SandyPluginInstance extends BasePluginInstance {
         );
       },
       onMessage: (event, cb) => {
-        this.events.on('event-' + event, batched(cb));
+        this.events.on(`event-${event.toString()}`, batched(cb));
       },
       onUnhandledMessage: (cb) => {
         this.events.on('unhandled-event', batched(cb));