Do not check nightly php builds, but 7.3 instead

Tim Helfensdörfer · web-flow · commit fd0a2253385c · 2019-03-23T13:07:45.000+01:00
diff --git a/.travis.yml b/.travis.yml
@@ -5,7 +5,7 @@ dist: trusty
 php:
   - 7.1
   - 7.2
-  - nightly
+  - 7.3
 
 before_script:
   - composer install
