try this?

iamcal · iamcal · commit 02351ce150b8 · 2019-03-01T01:20:34.000Z
diff --git a/.travis.yml b/.travis.yml
@@ -6,7 +6,7 @@ php:
   - '5.6'
   - '7.0'
   - '7.1'
-  - '7.4'
+  - '7.4.0'
   - hhvm-3.30
 
 install:
