www/gitlab-workhorse: fix build on armv7

This cast is a no-op on 64 bit platforms and prevents a type error
on 32-bit platforms.

Approved by: portmgr (build fix blanket)
PR: [[ https://bugs.freebsd.org/2026 | 2026 ]]Q2

(cherry picked from commit 4731beeec6f8dad167fa3b3ff8d4848aea26c2fc)