feat: add fetch_head configuration option into brew

[Wallunen]

Standards checklist:

• The PR title is descriptive.
• I have read CONTRIBUTING.md
• The code compiles (cargo build)
• The code passes rustfmt (cargo fmt)
• The code passes clippy (cargo clippy)
• The code passes tests (cargo test)
• Optional: I have tested the code myself

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If you developed a feature or a bug fix for someone else and you do not have the
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[SteveLauC]

Thanks! And congratulations on your first contribution to Topgrade!