add ericgpks as a reviewer to some rails dependency gems

[ericgpks]

By reading this issue #558, I would like to join as a reviewer in some gems.
I add me as a reviewer in this PR.

[github-actions]

@ericgpks Thanks for your contribution!

Please follow the instructions below for each change.
See also: https://github.com/ruby/gem_rbs_collection/blob/main/docs/CONTRIBUTING.md

Available commands

You can use the following commands by commenting on this PR.

• /merge: Merge this PR if CI passes

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aws-sdk-s3

You changed RBS files for an existing gem.
You need to get approval from the reviewers of this gem.

@ksss, please review this pull request.
If this change is acceptable, please make a review comment including APPROVE from here.

After that, the PR author or the reviewers can merge this PR.
Just comment /merge to merge this PR.

---

slack-notifier

You changed RBS files for an existing gem.
This gem does not have reviewers. So you can merge this PR immediately if the CI passes.
We recommend you add yourself to the reviewers for this gem.

[ksss]

@ericgpks
Thank you for expressing your intention.
However, I am sorry, but I am considering removing the aws-sdk gem from gem_rbs_collection. (I haven't deleted it yet because I haven't been able to verify what will happen if it's removed.)
Even if you are added as a reviewer, your first task will likely be to review the removal.

ref: #511

[ericgpks]

@ksss
Thank you for sharing the situation. I got it.

[ksss]

APPROVE

[github-actions]

Thanks for your review, @ksss!

@ericgpks, @ksss This PR is ready to be merged.
Just comment /merge to merge this PR.

[ericgpks]

/merge