Update rrwebPlayer types (#46)

Without this change, the following fails to compile in typescript:

```js
new rrwebPlayer({
                target: document.body,
                props: {
                    width: 900,
                    events,
                    autoPlay: true,
                },
            })
```

typings/index.d.ts

@@ -14,7 +14,7 @@ export default class rrwebPlayer extends SvelteComponent {
       speedOption?: number[];
       showController?: boolean;
       tags?: Record<string, string>;
-    } & playerConfig;
+    } & Partial<playerConfig>;
   });
 
   addEventListener(event: string, handler: (params: any) => unknown): void;