ci: remove broken npm self-upgrade step

@semantic-release/npm v13 handles OIDC token exchange itself via
@actions/core.getIDToken() so npm CLI 11.5.1+ is not required.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: patrickhulce

.github/workflows/ci.yml

@@ -22,7 +22,6 @@ jobs:
           node-version: '22'
       - name: apt-get install
         run: sudo apt-get update && sudo apt-get install build-essential libcairo2-dev libpango1.0-dev libjpeg-dev libgif-dev librsvg2-dev
-      - run: npm install -g npm@latest
       - run: corepack enable
       - run: yarn
       - run: yarn test