fix: remove global npm upgrade from publish workflow

The "npm install -g npm@latest" step was failing on the runner with a
MODULE_NOT_FOUND error for 'promise-retry' during npm's self-upgrade.
Node 22 already ships with npm 10.x which supports --provenance natively,
so the upgrade step is unnecessary.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: nikosd23

.github/workflows/npm-publish.yml

@@ -19,7 +19,6 @@ jobs:
         with:
           node-version: 22
           registry-url: https://registry.npmjs.org/
-      - run: npm install -g npm@latest
       - run: npm ci
       - run: npm run build
       - run: |