net/freerdp: Update 2.11.7 => 2.11.8, deprecate

"
This release will be the last official one for the 2.x series of FreeRDP.
From this point on we will no longer maintain this branch and urge all to
upgrade to FreeRDP 3.x.
"
Set EXPIRATION_DATE to 2026-12-31.

Changelog:
https://github.com/FreeRDP/FreeRDP/releases/tag/2.11.8

MFH: 2026Q1
(cherry picked from commit f12119901a1128f812f36cee29fd32c0f5174e64)