Fix an incorrect autocorrect for Style/RedundantDoubleSplatHashBraces

[koic]

This PR fixes the following incorrect autocorrect for Style/RedundantDoubleSplatHashBraces when using double splat hash braces with merge method call twice.

$ bundle exec rspec  spec/rubocop/cop/style/redundant_double_splat_hash_braces_spec.rb:82
Run options: include {:locations=>{"./spec/rubocop/cop/style/redundant_double_splat_hash_braces_spec.rb"=>[82]}}
(snip)

  Failures:

    1) RuboCop::Cop::Style::RedundantDoubleSplatHashBraces registers an offense
    when using double splat hash braces with `merge` method call twice
    Failure/Error: expect(new_source).to eq(correction)

      expected: "do_something(foo: bar, **options)\ndo_something(baz: qux, **options)\n"
           got: "do_something(foo: bar, **options)\ndo_something(baz: qux.merge(options))\n"

      (compared using ==)

      Diff:
      @@ -1,3 +1,3 @@
       do_something(foo: bar, **options)
      -do_something(baz: qux, **options)
      +do_something(baz: qux.merge(options))

# ./lib/rubocop/rspec/expect_offense.rb:164:in `expect_correction'
# ./spec/rubocop/cop/style/redundant_double_splat_hash_braces_spec.rb:90:in `block (2 levels) in <top (required)>'

Finished in 0.15475 seconds (files took 1.24 seconds to load)
1 example, 1 failure

---

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