Fix structural error - should NOT have fewer than 1 items

[laerciosb]

First of all, the project is amazing and is serving me perfectly. I hope it continues to evolve for a long time.
Well, I found a problem when generating the openapi from the request of a put method. The required field is generated empty and this results in an error when reading the file as shown in the images below:

To fix the error, I simply removed the required field if it was empty.

[exoego]

Thanks for the report and even a pull request!
The issue is reproducible with Swagger Editor on my side.

That place (inside cleanup_hash!) is a not place to be fixed.
cleanup_hash! used not only for paths field but also for many places, so adding that logic put unnecessary computation.

I think such empty array clean up added between ~~.cleanup! and ~~update! here:

rspec-openapi/lib/rspec/openapi/result_recorder.rb

Lines 27 to 29 in 7fc9e4a

	RSpec::OpenAPI::SchemaCleaner.cleanup!(spec, new_from_zero)
	RSpec::OpenAPI::ComponentsUpdater.update!(spec, new_from_zero)
	end

It would be great if you add test to verify new behavior.

I will look if you find it difficult.

[exoego]

@laerciosb Thanks for your PR.
I've fixed the issue in #111 and published v0.8.1.