chore: Update dependabot to capture package-lock.json (#3212)

# What does this PR do?
This should fix dependabot based on this thread:
https://stackoverflow.com/questions/60201543/dependabot-only-updates-lock-file


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## Test Plan
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Signed-off-by: Francisco Javier Arceo <farceo@redhat.com>

.github/dependabot.yml

@@ -19,3 +19,15 @@ updates:
       - python
     commit-message:
       prefix: chore(python-deps)
+
+  - package-ecosystem: npm
+    directory: "/llama_stack/ui"
+    schedule:
+      interval: "weekly"
+      day: "saturday"
+    labels:
+      - type/dependencies
+      - javascript
+    commit-message:
+      prefix: chore(ui-deps)
+      versioning-strategy: increase