Update .travis.yml for 7.4snapshot

jfcherng · jfcherng · commit 70f66a2f06da · 2019-04-29T04:43:07.000+08:00
Signed-off-by: Jack Cherng &lt;jfcherng@gmail.com&gt;
diff --git a/.travis.yml b/.travis.yml
@@ -4,6 +4,7 @@ php:
   - 7.1
   - 7.2
   - 7.3
+  - 7.4snapshot
 
 cache:
   directories:
