* Added support for authentication overrides when using a Google Service account
* It is now easier to override authentication credentials through
`$firebase->setAuthOverride($uid, array $claims = [])`.
* There's no need to create and set the needed custom tokens yourself.
* The new method works regardless of whether you use a database secret or
a Google Service Account for the basic authentication.
* Updated authentication docs
* Added methods:
* `Firebase::setAuthOverride(string $uid, array $claims = [])`
* `Firebase::removeAuthOverride()`
* Deprecated methods:
* `Firebase::setAuthToken()`
* `Firebase::getAuthToken()`
* `Firebase::hasAuthToken()`
* `Firebase::removeAuthToken()`