Can’t use in test

When you run component in `react-test-renderer` you get:

```
    TypeError: Cannot read property 'addEventListener' of null   
      at AnimakitExpander.toggleAnimationListener (node_modules/animakit-expander/lib/AnimakitExpander.js:142:20)
      at AnimakitExpander.componentDidMount (node_modules/animakit-expander/lib/AnimakitExpander.js:71:12)
```