Try to make npm ci work

`npm ci` fails on CI with an error message:

```
npm ERR! code EUSAGE
npm ERR!
npm ERR! `npm ci` can only install packages when your package.json and package-lock.json or npm-shrinkwrap.json are in sync. Please update your lock file with `npm install` before continuing.
npm ERR!
npm ERR! Missing: phoenix@1.7.2 from lock file
npm ERR! Missing: phoenix_html@3.3.1 from lock file
```

nodejs/node#46542

.github/workflows/ci.yml

@@ -57,7 +57,7 @@ jobs:
           cp config/test.ci.exs config/test.exs
 
       - run: mix deps.get
-      - run: npm ci
+      - run: npm ci --install-links=false
         working-directory: assets
 
       - name: Run tests