ci: add Dependabot for GitHub Actions version updates

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: reuvenharrison

.github/dependabot.yml

@@ -0,0 +1,10 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    groups:
+      actions:
+        patterns:
+          - "*"