Give travis a new job: monitor the starter files

.travis.yml

@@ -1,36 +1,50 @@
 os: linux
 dist: bionic
 
-language: ruby
+language: minimal
-rvm: 2.7.0
 
-cache:
+jobs:
+  include:
+
+    - name: CD
+      language: ruby
+      rvm: 2.7.0
+
+      addons:
+        apt:
+          packages:
+            # required to avoid SSL error (for htmlproofer)
+            - libcurl4-openssl-dev
+
+      cache:
         directories:
           - $TRAVIS_BUILD_DIR/vendor/bundle
 
-before_install:
+      before_install:
-  - gem install bundler:2.2.4   # match the Gemfile.lock, travis' bundle is 2.1.2
+        # match the Gemfile.lock, travis' bundler is 2.1.2
+        - gem install bundler:2.2.4
         - bundle config path 'vendor/bundle'
 
-install:
+      install:
         # overriding to drop the travis `--development` flag
         - bundle install --jobs=3 --retry=3
 
-addons:
+      script:
-  apt:
-    packages:
-      - libcurl4-openssl-dev  # required to avoid SSL error (for htmlproofer)
-
-script:
-  - git -C "$HOME" clone "$BUILDER_REPO" --depth=1 -q
         - eval "$BUILD_CMD"
 
+      git:
+        depth: false # for posts' lastmod
+
+    - name: Flush Starter
+      script:
+        - eval "$FLUSH_STARTER"
+
+before_script:
+  - git -C "$HOME" clone "$BUILDER_REPO" --depth=1 -q
+
 branches:
   only: /.*-stable$/
 
-git:
-  depth: false # for posts lastmod
-
 notifications:
   email:
     recipients: