fix typings for ctx.request.body

[imballinst]

For some reasons, the types aren't added into ctx.request.

[imballinst]

declare module 'koa' {
    interface Request {
        body?: any;
        rawBody: string;
    }
}

[imballinst]

This should be fixed in the latest thing, we need to have packageExtensions for @koa/bodyparser to have koa as peerDependencies, so that it could be picked up by the package manager resolves.

koajs/bodyparser#157