Upgrade react-docgen-typescript

[phoebejhhong]

Hi team, thank you for creating a great project. My team is excited to introduce Playroom into our toolset and it's so good to see Webpack 5 support has been released.

Another blocker of ours in react-docgen-typescript version. Prop autocomplete isn't working for our components because we are on Typescript 4.3. The error we're seeing was fixed in 2.0.0 with this change: styleguidist/react-docgen-typescript#360