Merge branch 'fix-go-version-docs-sync' into 'main'

Sync Go version checks across CI, mise.toml, and docs

Closes #39655

See merge request https://gitlab.com/gitlab-org/gitlab-runner/-/merge_requests/7079

Merged-by: Daniel Keenan <dkeenan@gitlab.com>
Approved-by: Daniel Keenan <dkeenan@gitlab.com>
Reviewed-by: GitLab Duo <gitlab-duo@gitlab.com>
Reviewed-by: Daniel Keenan <dkeenan@gitlab.com>
Co-authored-by: Lachlan Grant <lgrant@gitlab.com>