fix: bug in event typings after recent PR (#95)

Co-authored-by: Lars Johansson <gismya@gmail.com>

Author: ffMathy

source/event_hub.ts

@@ -59,16 +59,17 @@ export interface UpdateEventPayload extends BaseEventPayload {
  data: UpdateEventData;
 }
 
-export interface UnknownEventPayload extends BaseEventPayload {
- topic: unknown;
- data: unknown;
-}
-
+/**
+ * A union type of the different payload types with the
+ * `topic:` property as a type discriminator.
+ * Supports the topics `ftrack.action.discover`, `ftrack.action.launch`
+ * and `ftrack.update`. Please add a GitHub issue for any missing core topics.
+ * @interface EventPayload
+ */
 export type EventPayload =
  | ActionLaunchEventPayload
  | ActionDiscoverEventPayload
- | UpdateEventPayload
- | UnknownEventPayload;
+ | UpdateEventPayload;
 
 export interface EventSource {
  clientToken: string;