travis: run tests also on PHP 7.4 (#36)

JanTvrdik · dg · commit 9aea7a8f9962 · 2019-09-24T12:57:27.000+02:00
diff --git a/.travis.yml b/.travis.yml
@@ -3,6 +3,7 @@ php:
     - 7.1
     - 7.2
     - 7.3
+    - 7.4snapshot
 
 before_install:
     # turn off XDebug
