[Wishlist] Improve workflow to prevent GPG subkey to expire again next time

For issue like #40115 (closed) and #40299 (moved), we already experienced GPG subkey expiration a few times in the past. This caused downstream project like torbrowser-launcher failed to install TorBrowser, because it checks the download file integrity by GPG.

So I'm wondering whether we can improve GPG subkey fresh in your regular workflow, or add a timer notification. It's not urgent, but better to fix before next expiration date, Jan 04 2022. Thank you!