Add dependabot config for v4 (#30008)

.dependabot/config.yml

@@ -0,0 +1,23 @@
+# https://dependabot.com/docs/config-file/
+version: 1
+update_configs:
+  - package_manager: "javascript"
+    directory: "/"
+    update_schedule: "monthly"
+    target_branch: "v4-dev"
+    default_reviewers:
+      - "XhmikosR"
+    default_labels:
+      - "dependencies"
+      - "v4"
+    version_requirement_updates: "increase_versions"
+  - package_manager: "ruby:bundler"
+    directory: "/"
+    update_schedule: "monthly"
+    target_branch: "v4-dev"
+    default_reviewers:
+      - "XhmikosR"
+    default_labels:
+      - "dependencies"
+      - "v4"
+    version_requirement_updates: "increase_versions"