games/pioneer: unbreak after r446390

checking for ASSIMP... yes
checking for ASSIMP version >= 3.2... no
configure: error: "assimp version >= 3.2 not found. Get it from https://assimp.sourceforge.net/"

> Script "configure" failed unexpectedly.

PR: 220889
Pointy hat to: jbeich
Obtained from: upstream
Approved by: portmgr blanket