[CI] Add uv package ecosystem to dependabot

https://docs.github.com/en/code-security/reference/supply-chain-security/supported-ecosystems-and-repositories

Author: jbampton

.github/dependabot.yml

@@ -52,3 +52,15 @@ updates:
           - '*'
     cooldown:
       default-days: 7
+
+  - package-ecosystem: uv
+    directory: /
+    open-pull-requests-limit: 2
+    schedule:
+      interval: monthly
+    groups:
+      uv-dependencies:
+        patterns:
+          - '*'
+    cooldown:
+      default-days: 7