Use npm instead of yarn in lint workflow for consistency

The build workflow (publish-docs.yml) uses npm ci, so the lint
workflow should match to keep CI consistent.

Author: allgandalf

.github/workflows/lint.yml

@@ -19,10 +19,8 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: 20
-          cache: yarn
-
       - name: Install dependencies
-        run: yarn install --frozen-lockfile
+        run: npm ci
 
       - name: Lint
-        run: yarn lint
+        run: npm run lint