Annotate event-tracker test callback to satisfy typecheck

`payload.events` comes from `JSON.parse`, so after the narrow it's
`any[]` and the `.map` callback parameter trips noImplicitAny in the
generated SDK packages. Cast to a concrete element type before mapping.

Author: BilalG1

packages/template/src/lib/stack-app/apps/implementations/event-tracker.test.ts

@@ -19,7 +19,7 @@ function getSentEventTypes(sentBodies: string[]) {
     throw new Error("Expected analytics batch payload to include an events array.");
   }
 
-  return payload.events.map((event) => event.event_type);
+  return (payload.events as { event_type: string }[]).map((event) => event.event_type);
 }
 
 describe("EventTracker", () => {