Test on PHP 7.4

Author: GrahamCampbell

.travis.yml

@@ -1,14 +1,12 @@
 language: php
 
+dist: bionic
+
 php:
   - 7.1
   - 7.2
   - 7.3
-  - 7.4snapshot
-
-before_install:
-  - composer self-update
-  - composer clear-cache
+  - 7.4
 
 install:
   - travis_retry composer update --no-interaction --no-ansi --no-progress --no-suggest --optimize-autoloader --prefer-stable
@@ -21,4 +19,3 @@ after_success:
 
 notifications:
   email: false
-