added drone webhook

.drone.yml

@@ -26,3 +26,13 @@ cache:
   mount:
     - node_modules
     - /drone/pip-cache
+
+notify:
+  slack:
+    webhook_url: https://hooks.slack.com/services/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
+    channel: builds
+    username: drone
+    when:
+      success: true
+      failure: true
+      change: true