Update mergify to v2

Signed-off-by: Michal Konečný <mkonecny@redhat.com>

.mergify.yml

@@ -1,15 +1,24 @@
-rules:
-  default:
-    protection:
-      required_status_checks:
-        strict: true
-        contexts:
-          - DCO
-          - continuous-integration/travis-ci/pr
-      required_pull_request_reviews:
-        dismiss_stale_reviews: true
-        require_code_owner_reviews: true
-        required_approving_review_count: 1
-    merge_strategy:
+pull_request_rules:
+- actions:
+    merge:
       method: rebase
-      rebase_fallback: none
+      rebase_fallback: null
+      strict: true
+  conditions:
+  - label!=no-mergify
+  - approved-reviews-by=@fedora-infra/fedora-messaging-maintainers
+  - status-success=continuous-integration/travis-ci/pr
+  - status-success=DCO
+  name: default
+- actions:
+    merge:
+      method: rebase
+      rebase_fallback: null
+      strict: true
+  conditions:
+  - label!=no-mergify
+  - author=@fedora-infra/fedora-messaging-maintainers
+  - '#approved-reviews-by>=1'
+  - status-success=continuous-integration/travis-ci/pr
+  - status-success=DCO
+  name: default-from-fedora-messaging-team