https://gnupg.org/ftp/gcrypt/gnupg/
"GnuPG 2.4.x is the current stable branch of GnuPG"
This could be problematic for Homebrew's 2.5 gnupg package release, because a [Hombrew maintainer suggests keeping a "livecheck"](https://github.com/Homebrew/homebrew-core/pull/260913/files/7cc49c49aeb2c15dd9b74d19fc249debfde4245a) in the 2.5 package for even-numbered versions.