Update spec since Bugsnag::Stacktrace::VENDOR_PATH becomes Bugsnag::Configuration::DEFAULT_VENDOR_PATH
Update spec since Bugsnag::Stacktrace::VENDOR_PATH becomes Bugsnag::Configuration::DEFAULT_VENDOR_PATH

bugsnag/bugsnag-ruby,bugsnag/bugsnag-ruby,bugsnag/bugsnag-ruby,bugsnag/bugsnag-ruby