chore(deps): update dependency com_github_bazelbuild_buildtools to v6.4.0

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
com_github_bazelbuild_buildtools	http_archive	minor	v6.3.3 -> v6.4.0

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Release Notes

bazelbuild/buildtools (com_github_bazelbuild_buildtools)

### [`v6.4.0`](https://redirect.github.com/bazelbuild/buildtools/releases/tag/v6.4.0): Release 6.4.0 (2023-11-15) [Compare Source](https://redirect.github.com/bazelbuild/buildtools/compare/v6.3.3...v6.4.0) - More correct sorting order of load statements - Buildozer: better error reporting for missing comments - Suggested fixes for `package-on-top` warnings

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Configuration

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