Mergify: configuration update (#1200)

* Mergify: configuration update

* Update .mergify.yml

* Update .mergify.yml

* Update .mergify.yml

.mergify.yml

@@ -0,0 +1,36 @@
+pull_request_rules:
+
+  - name: Automatic merge on approval
+    conditions:
+      - base=master
+      # number of review approvals
+      - "#approved-reviews-by>=3"
+      # no waiting or assigned review
+      - "#review-requested=0"
+      # no requested chnages from any reviewer
+      - "#changes-requested-reviews-by=0"
+      # this serves as ALL check has to pass as we have actually 27 tests in total
+      - "#status-success=27"
+      # this is just in case since we rely on GPU tests (note: redundand to the above)
+      - status-success=continuous-integration/drone/pr
+      # this is patter-like, unofrunatly serves as `any(...)` (note: redundand to the above)
+      - "status-success~=^ci/circleci:"
+      # no conflict with master branch
+      - -conflict
+      # was not closed yet
+      - -closed
+    actions:
+      delete_head_branch: {}
+      merge:
+        strict: true  # https://doc.mergify.io/merge-action.html#strict-merge
+        strict_method: rebase
+        method: squash
+      comment:
+        message: Great job! =)
+
+  - name: warn on conflicts
+    conditions:
+      - conflict
+    actions:
+      comment:
+        message: This pull request is now in conflict... :(