update travis ci config (laradock#2412)

Author: bestlong

.travis.yml

@@ -24,11 +24,17 @@ env:
     - PHP_VERSION=hhvm BUILD_SERVICE=hhvm
 
     # - PHP_VERSION=5.6 BUILD_SERVICE=php-worker
-    - PHP_VERSION=7.0 BUILD_SERVICE="php-worker laravel-horizon"
-    - PHP_VERSION=7.1 BUILD_SERVICE="php-worker laravel-horizon"
-    - PHP_VERSION=7.2 BUILD_SERVICE="php-worker laravel-horizon"
-    - PHP_VERSION=7.3 BUILD_SERVICE="php-worker laravel-horizon"
-    - PHP_VERSION=7.4 BUILD_SERVICE="php-worker laravel-horizon"
+    - PHP_VERSION=7.0 BUILD_SERVICE=php-worker
+    - PHP_VERSION=7.1 BUILD_SERVICE=php-worker
+    - PHP_VERSION=7.2 BUILD_SERVICE=php-worker
+    - PHP_VERSION=7.3 BUILD_SERVICE=php-worker
+    - PHP_VERSION=7.4 BUILD_SERVICE=php-worker
+
+    - PHP_VERSION=7.0 BUILD_SERVICE=laravel-horizon
+    - PHP_VERSION=7.1 BUILD_SERVICE=laravel-horizon
+    - PHP_VERSION=7.2 BUILD_SERVICE=laravel-horizon
+    - PHP_VERSION=7.3 BUILD_SERVICE=laravel-horizon
+    - PHP_VERSION=7.4 BUILD_SERVICE=laravel-horizon
 
     - PHP_VERSION=NA BUILD_SERVICE=solr
     - PHP_VERSION=NA BUILD_SERVICE="mssql rethinkdb aerospike"