Updated Travis config

Author: florianv

.travis.yml

@@ -9,12 +9,10 @@ env:
 matrix:
     fast_finish: true
     include:
-        - php: 7.1
-          env: PREFER="--prefer-lowest"
         - php: 7.1
         - php: 7.2
         - php: 7.3
-
+        - php: 7.4
 cache:
   directories:
     - $HOME/.composer/cache