security/easy-rsa: update to v3.2.5

Also convert files/pkg-message.in to UCL
so it's also displayed on upgrade not only on install.

ChangeLog: https://github.com/OpenVPN/easy-rsa/releases/tag/v3.2.5
MFH: 2025Q4 in a few days (due to UCL pkg-message)
(cherry picked from commit 3d7e6c146a8a2734d77c5f11ec3e339ca0f6145d)