Patch release: lowers `go.mod`'s `go` directive from `1.26.1` (auto-set by `hugo mod init` from the maintainer's local toolchain) to a conservative `1.21`.
Submitted to themes.gohugo.io as part of hugoThemesSiteBuilder#706; the v1.1.1 build forced the upstream Netlify builder to upgrade Go from `1.25.9` → `1.26.2`, and the resulting toolchain change appears to have pulled in a newer `hugo!docs` that fails Tailwind compilation on Netlify's Node 18 environment. Kavu has no Go code, so the toolchain version is purely a minimum hint; `1.21` matches Hugo's own minimum and avoids forcing the upgrade.
No layout, CSS, JavaScript, or theme behaviour changes.