Enable Dependabot monthly GitHub Actions bumps (#159)

* chore: enable Dependabot weekly GitHub Actions bumps

* Monthly updates

---------

Co-authored-by: hf-dependantbot-rollout[bot] <285970069+hf-dependantbot-rollout[bot]@users.noreply.github.com>
Co-authored-by: Pedro Cuenca <pedro@huggingface.co>

Author: hf-dependantbot-rollout[bot]

.github/dependabot.yml

@@ -0,0 +1,11 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "monthly"
+    cooldown:
+      default-days: 7
+    groups:
+      actions:
+        patterns: ["*"]