Fix test case in file_path_spec.rb for `Style/RedundantStringEscape` by kkitadate · Pull Request #798 · rubocop/rubocop-rails

CI seems to have failed because rubocop/rubocop#11002 was merged. (e.g. 2723be4) This commit is for fixing it. Before submitting the PR make sure the following are checked: The PR relates to onl...