ci: install npm dependencies for cagent

Signed-off-by: David Karlsson <35727626+dvdksn@users.noreply.github.com>

.github/workflows/agent.yml

@@ -26,6 +26,9 @@ jobs:
           git config user.name "github-actions[bot]"
           git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
 
+      - name: Install dependencies
+        run: npm ci
+
       - name: Create branch
         run: |
           git checkout -b agent/issue-${{ github.event.issue.number }}