lang/go126: Update to 1.26.5
Changes:
go1.26.5 (released 2026-07-07) includes security fixes to the crypto/tls and os packages, as well as bug fixes to the compiler, the runtime, the go command, and the net, os, and syscall packages.
MFH: 2026Q3
Reviewed by: adamw
Differential Revision: https://reviews.freebsd.org/D58112