Fixed warning
Fixed warning

```
/home/travis/build/sue445/rubicure/vendor/bundle/ruby/2.5.0/gems/rspec-support-3.8.0/lib/rspec/support/object_formatter.rb:86: warning: wrong element type Rubicure::Girl at 0 (expected array)
/home/travis/build/sue445/rubicure/vendor/bundle/ruby/2.5.0/gems/rspec-support-3.8.0/lib/rspec/support/object_formatter.rb:86: warning: ignoring wrong elements is deprecated, remove them explicitly
/home/travis/build/sue445/rubicure/vendor/bundle/ruby/2.5.0/gems/rspec-support-3.8.0/lib/rspec/support/object_formatter.rb:86: warning: this causes ArgumentError in the next release
```

sue445/rubicure