This way we don't have to write `"spec/fixtures/files"` every time.
Note this method isn't included in factories. We could include it like
so:
```
FactoryBot::SyntaxRunner.class_eval do
include ActiveSupport::Testing::FileFixtures
self.file_fixture_path = RSpec.configuration.file_fixture_path
end
```
However, I'm not sure about the possible side effects, and since we only
use attachments in a few factories, there isn't much gain in applying
the monkey-patch.
4f232c3a25