Simplify travis matrix

.travis.yml

@@ -34,12 +34,9 @@ matrix:
   fast_finish: true
 
   include:
-    - php: 7.0
+    - php: 7.1
       env: PHPCS=1 DEFAULT=0
 
-    - php: 7.0
-      env: PHPSTAN=1 DEFAULT=0
-
     - php: 7.1
       env: PHPSTAN=1 DEFAULT=0