Merge pull request #2139 from alphagov/dependabot-merger-v2

Update dependabot merger config to v2, allow external dependencies to be automerged

.govuk_dependabot_merger.yml

@@ -1,30 +1,4 @@
-api_version: 1
-auto_merge:
-  - dependency: gds-api-adapters
-    allowed_semver_bumps:
-      - patch
-      - minor
-  - dependency: gds-sso
-    allowed_semver_bumps:
-      - patch
-      - minor
-  - dependency: govuk_app_config
-    allowed_semver_bumps:
-      - patch
-      - minor
-  - dependency: govuk_document_types
-    allowed_semver_bumps:
-      - patch
-      - minor
-  - dependency: govuk_personalisation
-    allowed_semver_bumps:
-      - patch
-      - minor
-  - dependency: govuk_sidekiq
-    allowed_semver_bumps:
-      - patch
-      - minor
-  - dependency: rubocop-govuk
-    allowed_semver_bumps:
-      - patch
-      - minor
+api_version: 2
+defaults:
+  auto_merge: true
+  update_external_dependencies: true