Fix scope error for Behat test

[sarahjcotton]

To fix the following the error when running Behat tests:

Failed hooks:

    AfterFeature # behat_hooks::after_feature()
      Type error: Argument 1 passed to behat_hooks::after_feature() must be an instance of FeatureEvent, instance of Behat\Behat\Hook\Scope\AfterFeatureScope given (Behat\Testwork\Call\Exception\FatalThrowableError)

    AfterFeature # behat_local_obf::teardownFeature()
      Type error: Argument 1 passed to behat_local_obf::teardownFeature() must be an instance of Behat\Behat\Event\FeatureEvent, instance of Behat\Behat\Hook\Scope\AfterFeatureScope given (Behat\Testwork\Call\Exception\FatalThrowableError)