Add compatibility with Ruby 3

[indirect]

Since Ruby 3 changed the way keyword arguments work, Rails now only accepts keyword arguments for find_in_batches. Unfortunately, the method_missing implementation on Elasticsearch::Model::Proxy doesn't proxy keyword arguments, so Rails now explodes. The error is triggered by calling Model.import, and looks something like this:

ArgumentError: wrong number of arguments (given 1, expected 0)
bundle/gems/activerecord-6.1.3.1/lib/active_record/relation/batches.rb:128:in 'find_in_batches'

The fix is to forward not just positional arguments, but also keyword arguments. This PR adds a test (failing before the patch), and a patch to forward keyword arguments.

Fixes #989, #977.

[cla-checker-service]

💚 CLA has been signed

[indirect]

I have now read and signed the contributor agreement.

[indirect]

I've updated the implementation to work on Ruby 2.4 through 3.0, based on this ruby-core blog post, which should keep this change backwards-compatible.

[picandocodigo]

Hi @indirect,
Thank you very much for this contribution! I'm working on a new release and I'd like to include this change. However, could you please restore this line? We need to keep the license header on every source code file.

Thanks!

[indirect]

Whoops, I must have accidentally deleted the first line when I opened the file and not noticed. Fixed.

[therrick]

Any outlook on merging this?

[tiendo1011]

@picandocodigo can you release a new version that includes this fix?
The newest one (7.2.0) is released before this fix is merged.
Thank you

[sebfie]

I also need this fix ! Please can you release a new version?

[jonnynux]

I upvote for releasing

[picandocodigo]

Version 7.2.1 has been released with these changes.

[mojobiri]

Would it be possible to add this patch to the 6.x version? We are using Elasticsearch 6 and would love to have Ruby 3 support in 6.1.2 too. Right now we have to monkeypatch.

[dersnek]

Would it be possible to add this patch to the 6.x version? We are using Elasticsearch 6 and would love to have Ruby 3 support in 6.1.2 too. Right now we have to monkeypatch.

#1053