Removed tests for PHP 5.6

Author: byjg

.travis.yml

@@ -14,10 +14,9 @@ php:
   - "7.2"
   - "7.1"
   - "7.0"
-  - "5.6"
 
 before_install:
-  - pecl install memcached
+  - echo "extension = memcached.so" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini
   - echo "extension = redis.so" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini
 
 install: