PHP 7.4 is no longer in "snapshot". (#460)

Author: desrosj

.travis.yml

@@ -3,7 +3,7 @@ dist: xenial
 language: php
 php:
     - master
-    - 7.4snapshot
+    - 7.4
     - 7.3
     - 7.2
     - 7.1
@@ -34,5 +34,5 @@ script:
     - ./.travis/travis.sh script $LIBMEMCACHED_VERSION
 
 cache:
-    directories: 
+    directories:
     - $HOME/cache