Update CI tools to exclude old PHP versions

.gitlab-ci.yml

@@ -8,15 +8,6 @@ cache:
 services:
     - redis:latest
 
-test:5.6:
-    before_script:
-      - bash build/docker_install.sh > /dev/null
-      - curl -sS https://getcomposer.org/installer | php
-      - php composer.phar install --no-dev
-    image: php:5.6
-    script:
-      - phpunit -c build
-
 test:7:
     before_script:
       - bash build/docker_install.sh > /dev/null

.travis.yml

@@ -4,8 +4,6 @@ install:
   - composer install
 
 php:
-  - 5.5
-  - 5.6
   - 7
   - hhvm
   - nightly
@@ -22,7 +20,6 @@ after_script:
 
 matrix:
   allow_failures:
-    - php: 5.5
     - php: nightly
     - php: hhvm