Adding Dependabot config

.github/dependabot.yml

+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: "/"
+    schedule:
+      interval: daily
+      time: "04:00"
+    reviewers:
+      - "waja"
+    pull-request-branch-name:
+      separator: "-"
+    open-pull-requests-limit: 10