[Fix #300] Fix Rails/RenderInline error on variable key in render options

[tejasbubane]

Closes: #300

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Before submitting the PR make sure the following are checked:

• 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.
• Added an entry to the Changelog if the new code introduces user-observable changes. See changelog entry format.
• If this is a new cop, consider making a corresponding update to the Rails Style Guide.
• The PR relates to only one subject with a clear title
  and description in grammatically correct, complete sentences.
• Run bundle exec rake default. It executes all tests and RuboCop for itself, and generates the documentation.

[eugeneius]

It's possible to write this cop entirely as a node pattern, which would also fix the bug:

        def_node_matcher :render_with_inline_option?, <<~PATTERN
          (send nil? :render (hash <(pair {(sym :inline) (str "inline")} _) ...>))
        PATTERN

        def on_send(node)
          add_offense(node) if render_with_inline_option?(node)
        end

[koic]

@tejasbubane Can you update this PR?

[tejasbubane]

@tejasbubane Can you update this PR?

@koic Done.

[koic]

Thanks!