[Fix #1423] Fix an error for Rails/StrongParametersExpect

[koic]

This PR fixes an error for Rails/StrongParametersExpect when using permit with no arguments.

Fixes #1423.

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• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Ran bundle exec rake default. It executes all tests and runs RuboCop on its own code.
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