Use pnpm audit in frontend CI job

Author: gildesmarais

.github/workflows/ci.yml

@@ -109,7 +109,7 @@ jobs:
         run: pnpm run format:check
 
       - name: Audit dependencies
-        run: npm audit --audit-level=moderate
+        run: pnpm audit --audit-level=moderate
 
       - name: Run frontend tests
         run: pnpm run test:ci