graphics/libwmf: update to 0.2.13

ChangeLog: https://github.com/caolanm/libwmf/releases/tag/v0.2.13

Fixes two crashes, one in gimp the other if no appropriate GS fonts are found.

Reported by: portscout
MFH: 2023Q2 (bugfixes)

(cherry picked from commit 809d0d3911ab6b34d61c2b16b8ac6dae44829aa6)