gnupg21: remove redundant comment
gnupg21: remove redundant comment

Closes https://github.com/Homebrew/homebrew/issues/40316

heuermh/homebrew-versions,UniqMartin/homebrew-versions,coeligena/homebrew-verscustomized,jimhe/homebrew-versions,Ashton-W/homebrew-versions,DomT4/homebrew-versions