Mergify: configuration update (#4)

.mergify.yml

@@ -0,0 +1,37 @@
+pull_request_rules:
+  - name: Automatic merge on approval
+    conditions:
+      - "#approved-reviews-by>=1"
+      - status-success=lint-test
+      - base=master
+      - label!=work-in-progress
+    actions:
+      merge:
+        method: merge
+
+  - name: delete head branch after merge
+    conditions:
+      - merged
+    actions:
+      delete_head_branch: {}
+
+  - name: remove outdated reviews
+    conditions:
+      - base=master
+    actions:
+      dismiss_reviews: {}
+      
+  - name: say hi on new contribution
+    conditions: []
+    actions:
+        comment:
+          message: |
+              Thanks for your pull request!
+              The owner of this repository will try to review and merge this as soon as possible.
+
+  - name: ask to resolve conflict
+    conditions:
+      - conflicts
+    actions:
+        comment:
+          message: This pull request has now conflicts with the base branch. Could you please try to fix them? 🙏