Cannot use with new version of RxJS (7.8.0 vs 5.5.12, for new Angular projects)

When trying to use this library you cannot use new RxJS operators, even simple ones like map.
Because the type of Observable does not match.

This forces many manual subscribes that could have been pipeline operators.

Minimal snippet (on new angular project with RxJS 7.8.0 and botframework-directlinejs 0.15.5):

return this.directLine.activity$.filter(x => x.type === 'message').pipe(map((x: Message): string => ''));

Possible solutions including making RxJS a peer dependency or upgrading it to a new version.

首先检查 botframework-directlinejs 0.15.5 如何声明 RxJS，以及 activity$ 入口点的类型定义方式。使用 RxJS 7.8.0 和 map 运算符复现 Angular 项目示例，然后确定是否需要修改依赖声明或 RxJS 兼容性。当该库能够在不进行手动订阅的情况下使用更新的 RxJS 类型时，即视为完成。