mail/py-notmuch2: Fix value of PKGNAMESUFFIX

In commit db96db170fc4, the value of PKGNAMESUFFIX was accidentally
changed from 2 to 0. Fix this by setting it back to the correct value,
2, which renames the package back to py*-notmuch2.

Bump PORTREVISION, so the renamed package is reinstalled with a
corrected plist.

PR: 298122
Reported by: John Hein <jcfyecrayz@liamekaens.com>
Fixes: db96db170fc4 (mail/notmuch*: Update to 0.34.2)
Sponsored by: The FreeBSD Foundation