ci: fix npm publish workflow failure on npm upgrade step

[federiconeri]

Problem

Publish run https://github.com/federiconeri/wiggum-cli/actions/runs/24093561110 failed in job 70286165217 at step "Upgrade npm for OIDC trusted publishing".

Error:

• npm install -g npm@latest
• MODULE_NOT_FOUND: Cannot find module promise-retry

Fix

• remove npm self-upgrade step from .github/workflows/publish.yml
• keep actions/setup-node@v6 + OIDC publish flow
• add check-latest: true so setup-node resolves latest patched Node 22 toolchain (and bundled npm patch level)

Why this is safe

• avoids fragile global npm mutation during publish
• keeps publish deterministic while still tracking patch updates in the selected major runtime line