enable nightly again, should work now

Author: mvdwerve

.travis.yml

@@ -10,7 +10,7 @@ php:
   - 7.0
   - 7.1
   - 7.2
-#  - nightly # doesn't work yet on PHP 7.3! not building.
+  - nightly # doesn't work yet on PHP 7.3! not building.
 
 
 # setting the env is the easiest, because it will mix with all the separate php versions (travis does this)