mail/fetchmail: update to 6.4.22 release.

This contains documentation updates, and one code change to the IMAP
client: IMAP: fix error code when LOGIN fails

This recently printed 'we've run out of authentication methods'
instead of the actual authentication failure.

This also formally adds OpenSSL 3.0.0 support.

PR: 258486
Approved by: Corey Halpin (maintainer)