ci: update pnpm setup

[liby]

Upgrading the pnpm/action-setup to v4 can prevent encountering these failed situations:

• https://github.com/element-plus/element-plus/actions/runs/9788077597/job/27027285287
• https://github.com/yazi-rs/yazi-rs.github.io/actions/runs/9786469651/job/27021395652

Upstream: pnpm/action-setup#135 (comment)

[joncinque]

Thanks for your contribution! How about just removing the:

with:
  version: 8

Bit everywhere since the version is specified in the package.json?

[liby]

Thanks for your contribution! How about just removing the:

with:
  version: 8

Bit everywhere since the version is specified in the package.json?

That's better. According to the document description of pnpm/action-setup

Omit version input to use the version in the packageManager field in the package.json.

[joncinque]

Thanks again for fixing this up!