nightly is now 8.0, which wont work (dependencies broken)

iamcal · iamcal · commit ce4625d0cf90 · 2019-03-01T00:45:39.000Z
peg to 7.4 which was the last one that worked
diff --git a/.travis.yml b/.travis.yml
@@ -6,7 +6,7 @@ php:
   - '5.6'
   - '7.0'
   - '7.1'
-  - nightly
+  - '7.4'
   - hhvm-3.30
 
 install:
