chore: update Travis CI Slack notifications

Author: Sam Harrison

.travis.yml

@@ -4,7 +4,7 @@ script:
   - make test
 
 after_success:
-    - bash <(curl -s https://codecov.io/bash)
+  - bash <(curl -s https://codecov.io/bash)
 
 deploy:
   skip_cleanup: true
@@ -13,3 +13,12 @@ deploy:
   on:
     branch: master
     tags: true
+
+notifications:
+  slack:
+    if: branch = master
+    on_pull_requests: false
+    on_success: never
+    on_failure: change
+    rooms:
+      - secure: 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