Brew: 4.6.8 Release

<!-- Release notes generated using configuration in .github/release.yml at main -->

What's Changed

• Load formulae from stubs in argument parser by @Rylan12 in https://github.com/Homebrew/brew/pull/20490
• Enable strict typing in Kernel extensions + utils.rb by @dduugg in https://github.com/Homebrew/brew/pull/20560
• Rename formula_support to keg_only reason, refactor slightly by @dduugg in https://github.com/Homebrew/brew/pull/20563
• Extract Pathname refinement from Formulary by @Rylan12 in https://github.com/Homebrew/brew/pull/20566
• formula_cellar_checks: avoid changing name by @cho-m in https://github.com/Homebrew/brew/pull/20571
• Remove redundant T.bind(self, Pathname) by @Rylan12 in https://github.com/Homebrew/brew/pull/20572
• Create DownloadQueue helper to check concurrency and initialize by @Rylan12 in https://github.com/Homebrew/brew/pull/20573
• Enable Sorbet/Refinement by @dduugg in https://github.com/Homebrew/brew/pull/20570
• dev-cmd/pr-publish: default to main branch by @cho-m in https://github.com/Homebrew/brew/pull/20574
• test, postinstall: use WriteMkpathExtension by @carlocab in https://github.com/Homebrew/brew/pull/20579
• bump: respect livecheck skipped status by @samford in https://github.com/Homebrew/brew/pull/20569
• Fix WriteMkpathExtension tests by @Rylan12 in https://github.com/Homebrew/brew/pull/20580
• Remove unnecessary use of T.must by @dduugg in https://github.com/Homebrew/brew/pull/20578
• Encourage using a default branch for HEAD core formulae by @issyl0 in https://github.com/Homebrew/brew/pull/20583
• unversioned_cask_checker: process rename operations by @bevanjkay in https://github.com/Homebrew/brew/pull/20584
• Include aliases and renames in FormulaStub by @Rylan12 in https://github.com/Homebrew/brew/pull/20586
• feat: update pod2man normalize by @daeho-ro in https://github.com/Homebrew/brew/pull/20589
• feat: update regex replace for pod2man by @daeho-ro in https://github.com/Homebrew/brew/pull/20594
• bundle/tap_installer: add force flag for official taps for developers. by @MikeMcQuaid in https://github.com/Homebrew/brew/pull/20596
• AbstractUninstall: coerce which argument to String by @samford in https://github.com/Homebrew/brew/pull/20595
• Allow "all" value for gnome_devel_allowlist by @samford in https://github.com/Homebrew/brew/pull/20597
• keg_only_reason locale: typed: strict by @botantony in https://github.com/Homebrew/brew/pull/20592
• Load replacement formula/cask from formula API by @Rylan12 in https://github.com/Homebrew/brew/pull/20598
• Bump the "all" group with 3 updates across multiple ecosystems by @dependabot[bot] in https://github.com/Homebrew/brew/pull/20602
• Revert "Use rubocop_internal formatter for Ruby LSP" by @Rylan12 in https://github.com/Homebrew/brew/pull/20604
• tap: actively check repo visibility by @ZhongRuoyu in https://github.com/Homebrew/brew/pull/20611
• DownloadStrategyDetector: handle tangled.sh Git URLs by @samford in https://github.com/Homebrew/brew/pull/20599
• lock_file simulate_system: typed: strict by @botantony in https://github.com/Homebrew/brew/pull/20608
• Avoid repeated calls to affix checks by @dduugg in https://github.com/Homebrew/brew/pull/20612
• Document MCP server capabilities by @ivy in https://github.com/Homebrew/brew/pull/20593
• Fix undefined method 'ohai' by @cho-m in https://github.com/Homebrew/brew/pull/20607
• Unlink old *_names.txt and *_aliases.txt files before overwriting by @Rylan12 in https://github.com/Homebrew/brew/pull/20618
• Add cask support to brew unpack command by @Copilot in https://github.com/Homebrew/brew/pull/20601

New Contributors

• @ivy made their first contribution in https://github.com/Homebrew/brew/pull/20593

Full Changelog: https://github.com/Homebrew/brew/compare/4.6.7...4.6.8