docs: fix use pnpm action-setup

[ccjr1120]

Description

Github Page

When I use pnpm according to the comments in the document

Github Action error

[build](https://github.com/ccjr1120/gpu-mesh/actions/runs/11361487910/job/31601296454#step:3:17)
Error: No pnpm version is specified.
Please specify it by one of the following ways:
  - in the GitHub Action config with the key "version"
  - in the package.json with the key "packageManager"

Linked Issues

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Additional Context

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