Cache key incorrectly uses 'x64' instead of '386' when architecture is set to '386' on Windows

Description:
When using architecture: '386' on a Windows runner, the cache key is incorrectly generated with the x64 suffix (e.g., setup-go-Windows-x64-go-1.22.12-${hash}). This prevents proper cache isolation between different architectures.

Action version:
v6.4.0

Platform:

• Ubuntu
• macOS
• Windows

Runner type:

• Hosted
• Self-hosted

Tools version:

• 1.22.12
• 1.23.12
• 1.24.13
• 1.25.8
• 1.26.1

Repro steps:
A description with steps to reproduce the issue. If your have a public example or repo to share, please provide the link.

    runs-on: windows-2025
    steps:
      - uses: actions/checkout@v6
      - uses: actions/setup-go@v6
        with:
          architecture: '386'

https://github.com/ryo-kagawa/go-utils/actions/runs/24959462267/job/73083475812

Expected behavior:
setup-go-Windows-386-go-1.22.12-${hash}

Actual behavior:
setup-go-Windows-x64-go-1.22.12-${hash}

Start by reproducing the issue with the provided Windows workflow using actions/setup-go@v6 and architecture '386'. Trace how the cache key is generated for the listed Go versions; done means the key uses Windows-386 rather than Windows-x64 and preserves architecture-specific cache isolation.