Adding stages to travis build

.travis.yml

@@ -22,18 +22,27 @@ env:
     - SYMFONY_DEPRECATIONS_HELPER=weak_vendors
     - TARGET=test
 
+stages:
+    - lint
+    - test
+
 matrix:
   fast_finish: true
   include:
-    - php: 7.2
+    - stage: lint
+      php: 7.2
       env: TARGET=lint
-    - php: 7.2
+    - stage: lint
+      php: 7.2
       env: TARGET=phpstan
-    - php: 7.1
+    - stage: test
+      php: 7.1
       env: COMPOSER_FLAGS="--prefer-lowest"
-    - php: 7.2
+    - stage: test
+      php: 7.2
       env: SYMFONY_VERSION=3.4.*
-    - php: 7.2
+    - stage: test
+      php: 7.2
       env: SYMFONY_VERSION=4.0.*
   allow_failures:
     - php: nightly