lang/go125: Update to 1.25.9
Changes:
go1.25.9 (released 2026-04-07) includes security fixes to the go command, the compiler, and the archive/tar, crypto/tls, crypto/x509, html/template, and os packages, as well as bug fixes to the go command, the compiler, and the runtime. See the Go 1.25.9 milestone on our issue tracker for details.
MFH: 2026Q2