chore(deps): update homebrew/ubuntu24.04 docker tag to v4.6.20

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
homebrew/ubuntu24.04 (source)	final	patch	4.6.19 -> 4.6.20

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Release Notes

Homebrew/brew (homebrew/ubuntu24.04)

v4.6.20

Compare Source

What's Changed

• Don't fail if a formula stub doesn't exist when checking Formula#outdated? by @​Rylan12 in #​20948
• Use formula stubs for shellcheck, shfmt, and actionlint operations in brew style by @​Rylan12 in #​20949
• dev-cmd/tests: remove HOMEBREW_USE_INTERNAL_API from test environment. by @​MikeMcQuaid in #​20950
• patches audit: add correctors by @​Moisan in #​20943
• Improvements to HOMEBREW_USE_INTERNAL_API by @​Rylan12 in #​20947
• Document HOMEBREW_USE_INTERNAL_API by @​MikeMcQuaid in #​20951
• github_runner_matrix: always deploy arm64 linux runner for bottling by @​cho-m in #​20957
• Add brew lgtm command to run multiple style checks in one command. by @​MikeMcQuaid in #​20958
• Bump the "all" group with 3 updates across multiple ecosystems by @​dependabot[bot] in #​20961
• download_queue: fix context bleeding out from threads. by @​MikeMcQuaid in #​20962
• resource_auditor: skip ftp.gnu.org audit by @​cho-m in #​20964
• checksum, version: improve .inspect output by @​MikeMcQuaid in #​20965
• dev-cmd/bump-cask-pr: add audit exceptions by @​bevanjkay in #​20939

Full Changelog: Homebrew/brew@4.6.19...4.6.20

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