amending travis config

run against more php versions

Author: SignpostMarv

.travis.yml

@@ -10,6 +10,12 @@ matrix:
       env: LINT=true
     - php: 7.2
       env: COMPOSER_FLAGS="--prefer-lowest"
+    - php: 7.3
+    - php: 7.3
+      env: COMPOSER_FLAGS="--prefer-lowest"
+    - php: 7.4
+    - php: 7.4
+      env: COMPOSER_FLAGS="--prefer-lowest"
 
   fast_finish: true