Remove global npm installation step

Removed global installation of npm version 11.

Author: mshima

.github/workflows/ci.yml

@@ -32,7 +32,6 @@ jobs:
         with:
           node-version: ${{ matrix.node-version }}
           cache: 'npm'
-      - run: npm install npm@11 -g
       - run: npm ci
       - run: npm test
         env: