Enable DependaBot to automatically update gems by default

Author: yasulab

.dependabot/config.yml

@@ -0,0 +1,17 @@
+version: 1
+update_configs:
+  - package_manager: "ruby:bundler"
+    directory: "/"
+    update_schedule: "daily"
+    allowed_updates:
+      - match:
+          update_type: "all"
+    automerged_updates:
+      - match:
+          dependency_type: "development"
+          update_type: "all"
+      - match:
+          dependency_type: "production"
+          update_type: "all"
+          #update_type: "semver:patch"
+    version_requirement_updates: "off"