lang/go126: Update to 1.26.1
Changes:
go1.26.1 (released 2026-03-05) includes security fixes to the crypto/x509, html/template, net/url, and os packages, as well as bug fixes to the go command, the go fix command, the compiler, and the os and reflect packages. See the Go 1.26.1 milestone on our issue tracker for details.