[macOS] Update Python installer script

[erik-bershel]

Description

• Default Homebrew Python 3 version installed to avoid re-linking if dependency
• Desired Python 3 version is selected by default

Related issue:

Check list

• Related issue / work item is attached
• Tests are written (if applicable)
• Documentation is updated (if applicable)
• Changes are tested and related VM images are successfully generated

[Copilot]

Pull Request Overview

Updates the Python installer script for macOS to handle Python version selection more effectively by installing the default Homebrew Python package first to avoid re-linking issues, then installing the desired Python 3 version (3.13) with forced linking.

• Added default Python version configuration (3.13) to all macOS toolset files
• Modified Python installation script to install default Homebrew Python before specific version
• Fixed test assertion pattern to include forward slash

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
toolset-26.json	Added Python default version configuration (3.13)
toolset-15.json	Added Python default version configuration (3.13)
toolset-14.json	Added Python default version configuration (3.13)
Python.Tests.ps1	Fixed test path pattern to include forward slash
install-python.sh	Restructured Python installation to handle dependencies and versioning

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