[compiler][ez] Upgrade babel generator version for playground

---
The current version of `@babel/generator` used by playground has some bugs (see babel/babel#10966)
```js
// Try pasting this into playground
function useFoo(a, b) {
  return (a ?? b) == c;
}

// Current playground output
function useFoo(a, b) {
  return a ?? b == c;
}
```

We previously locked babel library versions to be compatible with the oldest Meta internal usages. Now that both compiler and eslint plugins are bundled with rollup, this shouldn't be necessary.

ghstack-source-id: fa20d67
Pull Request resolved: facebook#30341

Author: felixshiftellecon