Add PHP 7.4 to test env.

vuongxuongminh · vuongxuongminh · commit 7b7f8f6f1fe1 · 2020-06-05T00:38:10.000+07:00
diff --git a/.travis.yml b/.travis.yml
@@ -4,6 +4,7 @@ php:
     - 7.1
     - 7.2
     - 7.3
+    - 7.4
 
 install:
     - composer self-update
