go 1.21.6

[stefanb]

Announcement: https://groups.google.com/g/golang-announce/c/F12eMaUITDs
Download: https://go.dev/dl/
Release notes: https://go.dev/doc/devel/release#go1.21.6

go1.21.6 (released 2024-01-09) includes fixes to the compiler, the runtime, and the crypto/tls, maps, and runtime/pprof packages. See the Go 1.21.6 milestone on our issue tracker for details.

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• Have you followed the guidelines for contributing?
• Have you ensured that your commits follow the commit style guide?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>)? If this is a new formula, does it pass brew audit --new <formula>?

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[github-actions]

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