onExited's arguments are different from docs

[r-tae]

Expected Behavior

The only documentation that shows the usage of onExited uses it with two arguments as such:

onExited: (event, myKey) => {
    // removen this snackbar from redux store
    dispatch(removeSnackbar(myKey));
    removeDisplayed(myKey);
}

This works in the CodeSandbox it's given in, but in the latest version the API is different

Current Behavior

the arguments appear to actually be (an element (?!), reason, key) though reason is undefined under normal circumstances. This is also the cause of #276.

Steps to Reproduce

Link: As Gareon noted in #276, this behaviour can be found in the redux example if you add a console.log statement
https://codesandbox.io/s/priceless-vaughan-rusvb?fontsize=14&hidenavigation=1&module=%2FNotifier.js&theme=dark

Context

Old messages in my store weren't being deleted and it was causing logic errors in my application

Your Environment

The environment doesn't affect this behaviour

Tech	Version
Notistack	v0.9.16

[iamhosseindhv]

This is bug caused by latest version of material-ui. meaning if you downgrade MUI core it'll start working:
mui/material-ui#21091

Alternatively and temporarily, you can access the key as the third argument.

[iamhosseindhv]

Dup of #276