pgp-expiry-monitor now skips revoked subkeys

I revoked a signing subkey of my GPG key.
The expiry date of this subkey will no longer be updated (as the key is revoked).
But I plan to keep the revoked subkey itself in my public key (so people can still associate old signatures with me).

The pgp-expiry-monitor would now alert for all eternity on the expiry date once it passes.
To avoid this, I now added functionality to read the revocation status of a subkey and skip the expiry date check if it has been revoked.

You can install the newest version of pgp-expiry-monitor from GitHub:

go install github.com/x-way/pgp-expiry-monitor@latest