Switched to new latest version of PHP 7.4

Author: dbalabka

.travis.yml

@@ -6,7 +6,7 @@ matrix:
     - php: '7.1'
     - php: '7.2'
     - php: '7.3'
-    - php: '7.4snapshot'
+    - php: '7.4'
 
 before_install:
   - phpenv config-rm xdebug.ini || echo "No xdebug config."