Update OpenBSD borgmatic link.

docs/how-to/set-up-backups.md

@@ -90,7 +90,7 @@ installing borgmatic:
  * [Fedora unofficial](https://copr.fedorainfracloud.org/coprs/heffer/borgmatic/)
  * [Arch Linux](https://www.archlinux.org/packages/community/any/borgmatic/)
  * [Alpine Linux](https://pkgs.alpinelinux.org/packages?name=borgmatic)
- * [OpenBSD](http://ports.su/sysutils/borgmatic)
+ * [OpenBSD](https://openports.pl/path/sysutils/borgmatic)
  * [openSUSE](https://software.opensuse.org/package/borgmatic)
  * [macOS (via Homebrew)](https://formulae.brew.sh/formula/borgmatic)
  * [macOS (via MacPorts)](https://ports.macports.org/port/borgmatic/)