biology/vsearch: Update to 2.32.0

Numererous bug fixes, new per-command man pages, and a few other
enhancements.
Changes: https://github.com/torognes/vsearch/releases
Normally I don't upgrade ports so close to the end of a quarter, but
this release has a lot of bug fixes, which I think outweigh the risk
of a regression slipping into the next quarterly branch.

Reported by: portscout