aider: use brewed pillow dependency

[chenrui333]

aider: use brewed pillow dependency

[Copilot]

Pull Request Overview

This PR configures the aider formula to use the system-provided Pillow dependency from Homebrew instead of building it from PyPI. This change aligns with Homebrew's best practice of reusing common dependencies across formulas.

• Adds "pillow" to the list of excluded PyPI packages for the aider formula
• Adds a dependency on the brewed "pillow" formula
• Removes the inline Pillow resource definition

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
pypi_formula_mappings.json	Adds "pillow" to the exclude_packages list for aider to prevent installing it from PyPI
Formula/a/aider.rb	Adds pillow as a formula dependency and removes the inline pillow resource block

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