Remove fastrlock from dependency

[Copilot]

This PR removes all references to the fastrlock package from the cupy-release-tools build environment.

Background

The dependency on fastrlock was removed from CuPy itself in cupy/cupy#9414. Since CuPy no longer requires fastrlock, it is no longer needed in the package build environment.

Changes

This PR removes fastrlock from all build configurations:

• Build configuration: Removed FASTRLOCK_VERSION constant from dist_config.py
• Docker builds (Linux): Removed fastrlock build arguments from dist.py and both Dockerfile variants (builder/Dockerfile and builder/Dockerfile.el8)
• Python setup script: Removed fastrlock installation from builder/setup_python.sh
• Windows builds: Removed fastrlock installation from .pfnci/wheel-windows/build.ps1

The changes are minimal and focused solely on removing fastrlock-related code without affecting any other functionality.

Testing

• All linting checks pass (ruff, autopep8)
• All type checking passes (mypy)
• Verified no remaining references to fastrlock in the codebase

Fixes #[issue_number]

Original prompt

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This section details on the original issue you should resolve

<issue_title>Remove fastrlock from dependency</issue_title>
<issue_description>Dependency to fastrlock has been removed in cupy/cupy#9414. The package is no longer required in the package build environment.</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #460

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[kmaehashi]

Will kick CI after merging #459

[kmaehashi]

/test mini

[kmaehashi]

/test mini

[kmaehashi]

This is ready @asi1024