apt-dater: Fix Homebrew/NoFileutilsRmrf offenses

[issyl0]

• Have you followed the guidelines for contributing?
• Have you ensured that your commits follow the commit style guide?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
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• Split this one out from the PR for the rest of the a* formulae (a*: Fix Homebrew/NoFileutilsRmrf RuboCop offenses #178118) because it had build failures that were unrelated.