chore: update Travis CI Slack notifications

.travis.yml

@@ -1,10 +1,10 @@
 language: node_js
 dist: xenial
 node_js:
-- lts/*
+  - lts/*
 before_install:
-- sudo apt-get update
-- sudo apt-get install -y libsecret-1-dev
+  - sudo apt-get update
+  - sudo apt-get install -y libsecret-1-dev
 deploy:
   - provider: script
     script: make docker-build && make docker-push
@@ -21,3 +21,12 @@ deploy:
     on:
       tags: true
       node: lts/*
+
+notifications:
+  slack:
+    if: branch = master
+    on_pull_requests: false
+    on_success: never
+    on_failure: change
+    rooms:
+      - secure: 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